Prof. Poggio at IIT

On the evening of the 13th, Prof. Poggio visited the Istituto Italiano di Tecnologia (IIT) outside of Genova, Italy. On the invitation of the director, Dr. Giorgio Meta, Prof. Poggio visited the labs and discussed potential collaborations between the IIT and the Swiss Nanoscience Institute (SNI). In the late morning, he gave a talk entitled, “Magnetic imaging on the nanometer scale”. 

End-of-year Group Dinner

On the evening of the 4th, the group held its annual year-end dinner, this time at Pizzeria Dio Mio in downtown Basel. 37 people showed up between group members, alumni, and friends and enjoyed a lively evening of food, drink, and conversation. See you next year!

PRL Publishes Paper on Coupling Ions to a Nanowire

On Monday the 25th, Physical Review Letters published a paper entitled, Coupling trapped ions to a nanomechanical oscillator, on our implementation of a hybrid system combining a metallic nanowire with laser-cooled ions in a miniaturized ion trap. Operating the experiment in the classical regime, we demonstrate resonant and off-resonant coupling of the two systems and the coherent motional excitation of the ion by the mechanical drive of the nanowire. The results prove the feasibility of mechanically coupling ions to nanooscillators and open up avenues for mechanically manipulating the motion of trapped ions as well as for the development of ion-mechanical hybrid quantum systems.

The work was carried out by Ph.D. student Moritz Weegen and pursued in the research group of Prof. Stefan Willitsch in the Department of Chemistry of the University of Basel. Prof. Poggio served as Moritz’s co-advisor on the project and advised the team as an expert in nanowire mechanics.

Liza Earns Ph.D. and Claire Donnelly Visits

On Thursday the 21st, Ph.D. student Liza Žaper defended her thesis, entitled, “Exploring nanomagnets for quantum devices with NV magnetometry”, earning her doctorate in physics cum laude. The defense was chaired by Prof. Andrea Hofmann with Dr. Claire Donnelly (MPI CPfS), Prof. Poggio, Prof. Patrick Maletinsky, and Dr. Floris Braakman making up the committee.

After obtaining her Masters degree from the Polytechnic University of Milan in Electronics Engineering and working at the ETH in Zürich, Liza joined our lab in September 2021. Finishing her doctorate in just over 3 years, Liza has managed to do so faster than any previous student in the lab. Congratulations to Dr. Žaper!

On the same day, our external expert, Dr. Claire Donnelly, visited the lab and the department. In the afternoon, she gave a special seminar entitled, “Exploring three dimensional spin systems – and beyond“.

Prof. Poggio in Dresden

On the 14th to the 15th, Prof. Poggio visited colleages in Dresden, Germany on the invitation of Dr. Denys Makarov of the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), just outside of Dresden. On Thursday the 14th, Prof. Poggio visited HZDR and gave a seminar entitled, “Magnetic microscopy of 2D and chiral magnetism”. The following day, Prof. Poggio visited colleagues including Dr. Thomas Mühl and Dr. Claire Donnelly at the Leibniz Institute for Solid-state and Materials Research (IFW) and the Max Planck Institute for Chemical Physics of Solids (MPI CPFS), respectively. He gave a seminar with the same title at MPI on the afternoon of Friday the 15th.

Estefani Speaks at Skymag 2024

From the 28th to the 30th, post-doctoral researcher Dr. Estefani Marchiori attended Skymag 2024 in Paris, France. The workshop concentrated on recent advances in the field of topological magnetic textures: in particular, the static and dynamic properties of skyrmions and antiskyrmions in ferromagnets and antiferromagnets,  the emergence of new skyrmionics materials, novel 2D and 3D topological structures as well as the applications of these magnetic textures. On the morning of the 28th, Estefani gave a talk entitled, “Imaging magnetic spiral phases, skyrmion clusters, and skyrmion displacements at the surface of bulk Cu₂OSeO₃“.

FIBsuperProbes Annual Meeting

On the afternoon of the 24th, our FET Open collaboration, ‘FIBsuperProbes‘ held its 4th and final annual meeting. The meeting was conducted online and included talks from members of each of the nodes: CSIC in Zaragoza, Spain; IBM Research in Zürich, Switzerland; University of Tübingen, Germany; and the coordinating node here at the University of Basel. The project is in its final year and will conclude in March 2025 with a final in-person meeting in Brussels, Belgium.

The project has produced remarkable results, especially in develping the SQUID-on-lever sensor technology that our group now employs for some magnetic imaging tasks. The original vision of the project was to enable a new era in scanning probe microscopy (SPM), in which nanometer-scale sensing devices – specifically superconducting devices – could be directly patterned on-tip and used to reveal new types of contrast. To realize this vision, we relied on focused ion beam (FIB) techniques to produce sensors with unprecedented size, functionality, and sensitivity directly on the tips of custom-designed cantilevers. The key to this undertaking has been the unique capability of FIB to mill, grow, or structurally modify materials – especially superconductors – at the nanometer-scale and on non-planar surfaces. The imaging techniques that resulted have significantly surpassed state-of-the-art SPM and are now helping us to unravel poorly understood phenomena in physics, chemistry, and material science.

Colloquium in Budapest

On the 22nd, Prof. Poggio gave the Leó Szilárd Colloquium at the Institute of Physics of the Budapest University of Technology and Economics with a talk entitled, “Magnetic microscopy of 2D and chiral magnetism”. Prof. Poggio also visited various researchers at the institute on the 21st and the 22nd, including collaborators Prof. Péter Makk and Prof. Sándor Bordács.

New shared Ph.D. starts

On the 7th, Patrick Raif started as an SNI Ph.D. student in both our group and the group of Prof. Andrea Hofmann in October 2024. Patrick received both his Bachelor of Science and Master of Science in Physics from the University of Konstanz in 2021 and 2024, respectively. For his Bachelor thesis, he spent 5 months working at the Institut Néel in Grenoble, France.

Nano Letters Publishes Paper on Strain in 2D Magnet CrSBr

On the 4th, Nano Letters published our article entitled, Imaging Strain-Controlled Magnetic Reversal in Thin CrSBr, on the role of inhomogeneous strain in the two-dimensional (2D) magnet CrSBr. 2D materials are extraordinarily sensitive to external stimuli, making them ideal for studying fundamental properties and for engineering devices with new functionalities. One such stimulus, strain, affects the magnetic properties of the layered magnetic semiconductor CrSBr to such a degree that it can induce a reversible antiferromagnetic-to-ferromagnetic phase transition. In this work, using scanning SQUID-on-lever microscopy, we directly image the effects of spatially inhomogeneous strain on the magnetization of layered CrSBr, as it is polarized by a field applied along its easy axis. The evolution of this magnetization and the formation of domains is reproduced by a micromagnetic model, which incorporates the spatially varying strain and the corresponding changes in the local interlayer exchange stiffness. The observed sensitivity to small strain gradients along with similar images of a nominally unstrained CrSBr sample suggest that unintentional strain inhomogeneity influences the magnetic behavior of exfoliated samples.

The study was led by Ph.D. student Andriani Vervelaki and former post-doctoral researcher Dr. Kousik Bagani. The latter two carried out the imaging experiments with support from Ph.D. student Daniel Jetter, who produced the SQUID-on-lever sensors. Research scientist Dr. Boris Groß provided input on the micromagnetic simulations. Collaborators from Columbia University in the groups of Profs. Xavier Roy and Cory Dean provided the 2D magnet samples. Former Ph.D. student and current post-doctoral researcher Märta Tschudin from Prof. Patrick Maletinksy’s group here in Basel helped conceive the collaborative project, after measurements on similar samples were carried out in the Maletinsky group.

Francesco and Aris at Workshop in Grenoble

From September 30th to October 1st, post-doctoral researcher Dr. Francesco Fogliano and Ph.D. student Aris Lafranca attended the 9th annual GDR MecaQ & Nanomeca Meeting in Grenoble, France. This meeting gathers the community of scientists — in France and nearby countries — sharing an interest for quantum optomechanics, nanomechanics, and associated phenomena and applications. Francesco gave a talk on the 1st entitled, “hBN optomechanical induced transparency and gain”, while Aris presented a poster, for which he won the best poster prize. Congratulations!

Mirco at Summer School in Trieste

From September 23rd to October 4th, Masters student Mirco Schwarz atteded the School and Workshop on Frontiers of Nanomechanics at the International Cetre for Theoretical Physics (ICTP) in Trieste, Italy. The school covered fundamental concepts of nano- and optomechanical systems and introduced the key concepts behind future nano- and optomechanical technologies. It included lectures on coupling nanomechanics to spins, nonlinear dynamics, topological systems, cavity optomechanics, foundations, coupling to qubits, and non-Hermitean physics. The lectures reflected the fields, which currently attract the highest scientific interest and/or application potential. The students also worked on mini-projects and had the chance to present their work in a poster session.

Paper Published on Imaging Magnetic Phases in Cu₂OSeO₃

On the 28th, Communications Materials published our article entitled, Imaging magnetic spiral phases, skyrmion clusters, and skyrmion displacements at the surface of bulk Cu₂OSeO₃, in which we use scanning SQUID microscopy to image the surface of bulk Cu₂OSeO₃ at low temperature. Real-space maps measured as a function of applied field reveal the microscopic structure of the magnetic phases and their transitions. In low applied field, we observe a magnetic texture consistent with an in-plane stripe phase, pointing to the existence of a distinct surface state. In the low-temperature skyrmion phase, the surface is populated by clusters of disordered skyrmions, which emerge from rupturing domains of the tilted spiral phase. Furthermore, we displace individual skyrmions from their pinning sites by applying an electric potential to the scanning probe, thereby demonstrating local skyrmion control at the surface of a magnetoelectric insulator.

The work was led by post-doctoral researcher Dr. Estefani Marchiori, who along with former Ph.D. student Dr. Giulio Romagnoli carried out the experiments and analyzed the data. Ph.D. student Lukas Schneider did the magnetic force microscopy (MFM) measurements using ultrasensitive magnet-tipped nanowires (NWs) and research scientist Dr. Boris Groß carried out micromagnetic simulations. The Cu₂OSeO₃ crystals were grown by Dr. Priya Baral and Dr. Arnaud Magrez from EPFL, while the NWs for MFM were grown by collaborators in the Budakian group at the University of Waterloo, Canada. Together with Estefani, Dr. Jonathan White from the PSI carried out small angle neutron scattering measurements on the sample. The project was the result of collaborations started during the ‘Nanoskyrmionics’ Sinergia Project led by Prof. Dirk Grundler from EPFL.

Group trip to Crete

From the 19th to the 22nd, a subset of the group and friends traveled to the island of Crete, Greece for a weekend of sun, food, and outdoor activities. Special thanks to Ph.D. student Andriani Vervelaki for organizing and serving as our local guide to her beautiful island.

Swiss Physical Society Meeting

From the 9th to the 13th, the Swiss Physical Society (SPS) Annual Meeting was held at the ETH Zürich. Prof. Poggio attended a session on “Spintronics and magnetism at the nanoscale” on Tuesday the 10th and Thursday the 12th. He gave a talk in this session on the 10th entitled, “Scanning SQUID-on-tip microscopy of 2D and chiral magnetism”.

2024 SNI Annual Meeting

From the 4th to the 6th, students Lukas Schneider, Luca Forrer, and Prof. Poggio were in Meisterschwanden, Switzerland for the 2024 Swiss Nanoscience Institute’s Annual Meeting. For the second time, the meeting was held on the banks of lake Hallwil at the Hotel Seerose. Lukas and Luca both presented posters and Prof. Poggio hosted the proceedings in his role as SNI director.

New Group Members

Two new members recently started work in our group. Mirco Schwarz, who did his Masters Project in our lab, decided to continue working in the group and pursue his Masters degree with us. Mirco earned his Bachelor of Science in Physics in 2023 from the University of Basel and his project will focus on the mechanical properties of 2D magnetic materials. Dr. Damien Richert started work as a post-doctoral researcher in our group in the 2nd. Damien earned his Bachelors in Engineering from the Polytechnic Institute Clermont-Ferrand in 2014. He then went to Prof. Michael Santos’ group at the University of Oklahoma to work on III-V heterostructure characterization, earning his Masters in 2019. From 2021 to 2024, he worked at the Laboratoire National de Metrologie et d’Essais (LNE) under Dr. Francois Piquemal and Prof. Brice Gautier. There he earned his Ph.D. from the University of Lyon in 2024. In our group, he will concentrate on imaging of superconducting devices designed for quantum computing. Welcome to both Mirco and Damien!

Machine Shop / Poggio Lab BBQ

On Friday the 23rd, we had our annual barbecue on teh derpartment’s roof-top with our friends and colleagues from the Machine Shop, Electronics Shop, administrative staff, and friends. Fromer administrative staff Audrey Fischer and Barbara Kammermann also joined us for a pleasant time under the evening sun. Thanks to all who helped organize and see you next year!

Research Scientist Starts in Lab

On the 9th, Dr. Paritosh Karnatak started as a research scientist in our group. Dr. Karnatak received his Bachelors and Masters from the Indian Institute of Technology Kanpur, graduating in 2011. In 2018, he obtained his Ph.D. at Indian Institute of Science in the Low-Temperature Nanoelectronics group with Prof. Arindam Ghosh. From that time until July 2024, he worked as a post-doctoral researcher in the group of Prof. Christian Schönenberger here at the Department of Physics of the University of Basel. His past research has focused on superconducting phenomena in van der Waals (vdW) heterostructures. He has studied electronic transport in a variety of materials: vdW superconductors, graphene Josephson junctions and twisted graphene systems.Welcome Paritosh!

Prof. Poggio at FEBIP 2024

From the 21st to the 24th, Prof. Poggio attended the 2024 edition of the biennial Focused Electron Beam Induced Processing (FEBIP) workshop in Frankfurt, Germany. The workshop aimed to provide a platform for the scientific community working with focused electron beams as a tool for direct nanofabrication, through gas-assisted deposition and etching. However, the workshop also included the inherently related Focused Ion Beam Induced Processing (FIBIP) and related techniques. Prof. Poggio gave a talk on the 24th entitled, “Focused ion beam fabrication of superconducting scanning probes”.

Andriani Speaks at Workshop on Magnetic Materials

From the 16th to the 18th, Ph.D. student Andriani Vervelaki attended the Young Research Leaders Group Workshop: Correlation and Topology in Magnetic Materials in Ingelheim, Germany. The workshop aimed to get a broad perspective of one of both correlation and topology in magnetic materials, which is one of the hottest topics in condensed matter physics today. The workshop included researchers from both experiment and theory and sought to promote collaborations across different perspectives. Andriani gave an invited talk on Wednesday the 17th entitled, “Controlling magnetic domain evolution via strain in CrSBr“.

Collaboration with Maletinsky Group

On the 17th, Nature Communications published a paper by Märta Tschudin, a Ph.D. student in the Maletinsky group, entitled, Imaging nanomagnetism and magnetic phase transitions in atomically thin CrSBr. Therein, the authors use scanning nitrogen-vacancy magnetometry to characterize the few-layer antiferromagnet CrSBr. The work represents a collaboration across a number of groups, led by Prof. Patrick Maletinsky. From our group, research scientist Dr. Boris Groß carried out micromagnetic simulations to compare to the experimental measurements.

Paper by Warburton Group on MoS₂ Published

On the 8th, Physical Review Letters published work on optical measurements of the monolayer semiconductor MoS₂ by former Ph.D. student in the Warburton group, Dr. Nadine Liesgang. The manuscript presents evidence for a spin polarized state of the mobile electrons. From our group, former Ph.D. student Hinrich Mattiat and current Ph.D. student Lukas Schneider collaborated on the project, especially in the fabrication of devices and assisting in optical measurements. The work is entitled, Exchange Energy of the Ferromagnetic Electronic Ground State in a Monolayer Semiconductor.

Aris Wins Best Masters Thesis

This year’s prize for the best master’s thesis in nanosciences at the University of Basel goes to Aris Lafranca, who did the thesis in our group and has since started as a Ph.D. student. As part of the winning master’s thesis at the Department of Physics, Aris investigated the mechanical properties of a hBN mechanical drum resonator.

Floris Attends Second Kick-off Meeting

From the 19th to the 21st, research scientist Dr. Floris Braakman represented the group at the kick-off meeting for our second new EuraMet collaborative project, entitled, “Quantum Anomalous Hall Effect materials and Devices for Metrology (QuAHMET)”. The meeting took place in Prague, Czech Republic and included two days of presentations and discussions.

The Quantum Hall effect (QHE) is the foundation for the realization of the primary resistance standard (PRS) in electrical metrology. QHE devices currently require low temperatures and high magnetic fields, impeding their adoption beyond national metrology institutes. The Quantum Anomalous Hall effect (QAHE) provides an opportunity to overcome these limitations while maintaining the unsurpassed accuracy expected of PRS. Greater knowledge of QAHE devices is essential to accelerate the development of a ‘quantum electrical metrology toolbox’ for the universal adoption of quantum electrical SI standards. This project aims to grow, characterize, and evaluate thin films for QAHE devices, leading to a detailed metrological assessment from sub-K to above 1 K, currents from below 100 nA to above 1 µA and over a wide range of external magnetic fields up to several Tesla. Our group’s role in the project is to characterize samples using scanning SQUID and scanning microwave microscopy.

Luca Forrer Speaks at SPIN Annual Meeting

From the 12st to the 14th, Ph.D. student Luca Forrer attended the 4th Annual Meeting of the NCCR SPIN in Pontresina, Switzerland. On the afternoon of Friday the 14th, he gave a talk entitled, “Scanning multi-gate and quantum dot microscopy”.

Prof. Poggio in Finland

From the 10th to June 13th, Prof. Poggio attended the MQSens Workshop on “Quantum sensing with nonclassical mechanical oscillators” near Helsinki, Finland. The aim of the workshop was to bring together experts and young researchers from the fields of quantum sensing and opto-/electromechanics in order to explore how quantum protocols can be adapted to mechanical sensors in the quantum regime for various applications. The conference was held at the Hotel Nuuksio and was chaired by Prof. Mika Sillanpää (Aalto University). Prof. Poggio gave a talk on the 13th entitled, “Using nanomechanics to study nanomagnetism”.

Floris at MetSuperQ Kick-off

On the 6th and 7th, Dr. Floris Braakman represented the group at the kick-off meeting for our new EuraMet collaborative project entitled, “Metrology for superconducting qubits (MetSuperQ)”. The meeting was held at the PTB in Braunschweig, Germany.

The project aims to address challenges in optimizing qubit coherence reproducibility, stability, control and readout in superconducting circuits for quantum computing. For this task, a new generation of metrological methods and tools will be needed. This project will develop such a suite of tools for superconducting qubits and apply them to state-of-the-art one- and two-qubit circuits. These new tools will underpin further engineering advances and allow for accurate characterisation of qubits and materials, as well as manipulation and read-out. Our group will contribute with scanning probe methods, including scanning SQUID microscopy.

Lukas at Quantum Sensing Conference in Paris

From the 4thto the 6th, Ph.D. student Lukas Schneider attended the International Conference on “Quantum Sensing” at the Collège de France in Paris, France. The conference aimed to bring together two scientific communities: the one focusing on fundamental aspects of the quantum phenomena in superconducting hybrids and the other working on the development of quantum devices and detectors, pushing the frontiers of their sensitivity and their range of applications, inventing new technological and conceptual routes. Lukas presented a poster on his latest nanowire-based magnetic force microscopy work.

Group Members at Attocube 2D Materials Conference

From the 3rd to the 8th, Ph.D. students Daniel Jetter and Andriani Vervelaki attended the 2D Materials Conference outside of Munich in Haar, Germany. The conference was organized by Attocube AG and included an impressive roster of invited speakers presenting the latest results in this fast-moving field. Andriani presented a poster on teh 6th entitled, “Controlling magnetic domain evolution via strain in CrSBr”. After completing his duties as host of the Swiss Nanoconvention, Prof. Poggio joined the conference on the 6th and gave an invited talk on the 7th entitled, “Scanning SQUID-on-tip microscopy of 2D and chiral magnetism”.

Swiss Nanoconvention in Basel

The Swiss Nanoscience Institute (SNI), of which Prof. Poggio is the director, hosted the 2024 edition of the Swiss Nanoconvention at the Basel Convention Center from the 4th to the 5th. A list of internationally reknowned speakers presented their latest results from the various corners of nanoscience, including materials physics, nanomedicine, and chemistry. From physics, highlights included keynote speakers Prof. Kam Moler (Stanford), Prof. Simon Gröblacher (Delft), and former director Prof. Christian Schönenberger, as well as sessions on quantum materials, 2D materials, optomechanics. Thanks to the SNI management team (especially Kerstin Bayer-Hans) for a wonderful job organizing this successful meeting!

Group Trip to Ligerz

From the 31st to June 2nd, 9 group members travelled to Ligerz, Switzerland for a relaxing group weekend at the Aarbergerhus. Ligerz is a small village on the shore of Lake Biel in the Canton of Bern. Despite the rainy weather forecast, Saturday proved to be a perfect day allowing for hiking to the Twannbachschlucht and a short boat trip and hike around St. Peterinsel. Thanks to Ph.D. student Luca Forrer for the organization and all for the good times!

Roadmap on Nanoscale Magnetic Resonance Imaging Published

On the 14th, Nanotechnology published a ‘roadmap’ article nanoscale magnetic resonance imaging (NanoMRI). The work is entitled, Roadmap on nanoscale magnetic resonance imaging. It reports on the current state of the art in NanoMRI technologies, it outlines the areas where they are poised to have impact, it identifies the challenges that lie ahead, and it proposes methods to meet these challenges. Prof. Raffi Budakian (Waterloo) led the team putting together the article, which included Prof. Amit Finkler (Weizmann) and Prof. Alex Eichler (ETHZ). Prof. Poggio contributed the first chapter on magnetic resonanance force microscopy.

Prof. Poggio in Leoben

On the 13th, Prof. Poggio visited the lab of Prof. Aleksandar Matkovic at the Montanuniversität in Leoben, Austria. Along with touring the labs and discussing with Prof. Matkovic and his colleagues about an ongoing collaboraiton, Prof. Poggio gave a seminar entitled, “Scanning SQUID-on-tip microscopy of 2D and chiral magnetism “.

Prof. Aleksandar Matkovic Visits

Prof. Aleksandar Matkovic from the Montanuniversität in Leoben, Austria visited from on Monday the 29th. He gave a talk at the Quantum & Nano Seminar on Monday afternoon entitled, “Sheet silicate clays as functional gate insulators for two dimensional materials-based electronics”. He also visited our lab and spent time discussing an ongoing collaboration with members of the group.

Andriani and Daniel in Valencia

From the 21st to the 25th, Ph.D. students Andriani Vervelaki and Daniel Jetter attended the “European School on Superconductivity and Magnetism in Quantum Materials” in Valencia, Spain. The school provided a comprehensive series of foundational lectures, while also delving into the latest developments in the fields of superconductivity and magnetism. Cutting-edge advancements within these interdisciplinary fields were also discussed, as well as the synergies between superconductivity and magnetism.

Ph.D. Student Joins group

On the 10th, Antonella Restino joined the group as a Ph.D. student. Antonella received her Bachelor of Science in Physics in 2020 from University of Campania Luigi Vanvitelli in Italy. She went on to get her Masters degree in Physics in 2023 from the University of Naples Federico II under Profs. Tafuri and Massarotti. She has now moved to Basel for her Ph.D. Welcome!

Visit of Laura Heyderman

On the 22nd, Prof. Laura Heyderman from the PSI and ETH Zürich visited our department to give the Colloquium on the invitation of Prof. Poggio. Her talk was entitled, “Recent advances in artificial spin ice”. Prof. Heyderman spent the day in the Deparment and visited the group to discuss ongoing research.

High-school students visit lab

On the 21st, students in the final year of a high school from the Istituto d’Istruzione Superiore “James Clerk Maxwell” in Milano, Italy visited the department, on the invitation of Prof. Ilaria Zardo. As part of the visit, 2 groups of the 49 students were given a tour of our lab by post-doctoral researcher Dr. Francesco Fogliano, Ph.D. student Aris Lafranca, and Prof. Poggio. Further tours included the labs of Prof. Philipp Treutlein and Prof. Ilaria Zardo.

Paper on Magnetic Imaging of 2D Cr₂Ge₂Te₆ Published

On the 19th, Communications Materials published our article entitled, Visualizing thickness-dependent magnetic textures in few-layer Cr₂Ge₂Te₆. Therein we describe magnetic imaging experiments on few-layer Cr₂Ge₂Te₆ using a combined scanning superconducting quantum interference device and atomic force microscopy probe. Maps of the material’s stray magnetic field as a function of applied magnetic field reveal its magnetization per layer as well as the thickness-dependent magnetic texture. Using a micromagnetic model, we correlate measured stray-field patterns with the underlying magnetization configurations, including labyrinth domains and skyrmionic bubbles. By Comparing between real-space images and simulations, we demonstrate that the layer dependence of the material’s magnetic texture is a result of the thickness-dependent balance between crystalline and shape anisotropy. These findings represent an important step towards 2D spintronic devices with engineered spin configurations and controlled dependence on external magnetic fields.

The study was led and carried out by former post-doctoral researcher Dr. Kousik Bagani and Ph.D. students Andriani Vervelaki and Daniel Jetter. Research scientist Dr. Boris Groß provided input on the micromagnetic simulations. Samples were fabricated by members of the group of Prof. Peter Bøggild (DTU). Prof. Dennis Christensen (DTU) initiated the collaboration.

Roadmap on Magnetic Microscopy Published

On the 8th, Journal of Physics: Materials published a ‘roadmap’ article, in which experts in different areas of magnetic microscopy provide their views on the current capabilities of available techniques, forecast future advances, and assess how such advances may impact materials science. The work is entitled, 2024 Roadmap on Magnetic Microscopy Techniques and Their Applications in Materials Science. The focus of the article is on material science and physics. Prof. Dennis Christensen (DTU) led the team putting together the article, which included Dr. Urs Staub (PSI), Prof. Nini Pryds (DTU), Prof. Denys Makarov (HZD Dresden), and Prof. Poggio.

New Masters Students

Early this year, 3 new students have joined the group to pursue their Masters theses: Loris Durante, Katharina Kress, and Moritz Haberthür. Both Loris and Katharina have already worked in the group as part of one of their Masters projects. We welcome all three to the group and wish them luck on their projects!

Party for Kousik

On the 23rd, the group held a farewell party for Dr. Kousik Bagani, who will be leaving the group at the end of the month. Kousik joined the group in the midst of the COVID-19 pandemic in October 2020, after a post-doc in the lab of Prof. Eli Zeldov (Weizmann). Since then, he has led our efforts on developing SQUID-on-lever probes and applying them to the study of 2D magnets. He has also helped manage our FIBsuperProbes collaboration, taking over for Dr. Marcus Wyss. Kousik is now moving to Munich to start a job at Attocube AG. We wish him the best of luck in this new adventure and hope to continue working with him for a while longer on the projects he started. His contributions to the group — scientific and otherwise — will be missed by all!

NW MFM of bilayer EuGe₂

On the 15th, Nanoscale published our article entitled, Mapping the phase-separated state in a 2D magnet, as an “accepted manuscript” before the final edited and formated version appears. In the paper, we employ a high-sensitivity magnetic force microscopy (MFM) technique, using a nanowire (NW) transducer, to probe the spatial distribution of magnetic states in the paradigmatic 4f 2D ferromagnet EuGe₂. Below the ferromagnetic transition temperature, we discover the phase-separated state and follow its evolution with temperature and magnetic field. The characteristic length-scale of magnetic domains amounts to hundreds of nanometers. These observations strongly shape our understanding of the magnetic states in 2D materials at the monolayer limit and may contribute to engineering of future ultra-compact spintronic devices.

The research was carried out in our group by former Ph.D. student Dr. Hinrich Mattiat and current Ph.D. student Lukas Schneider, who did the MFM. The collaboration included Ph.D. student Patrick Reiser (Basel) and members of the Budakian group (University of Waterloo), who provided the NW MFM transducers. Members of the group of Prof. Vyacheslav Storchak (Kurchatov Institute) grew the EuGe₂ samples, carried out experiments using complementary techniques, and did analysis of the measurements. 

Scanning NV Magnetometry of Nanomagnets

On the 7th, ACS Applied Nano Materials published our article entitled, Scanning Nitrogen-Vacancy Magnetometry of Focused-Electron-Beam-Deposited Cobalt Nanomagnet. The work discusses the patterning of nanomagnets via focused-electron-beam-induced deposition (FEBID).  We report on the fabrication of cobalt nanomagnets and characterize their content, saturation magnetization, and stray magnetic field profiles, using a combination of transmission electron microscopy and scanning nitrogen-vacancy magnetometry. We find agreement between the measured stray field profiles and saturation magnetization with micromagnetic simulations. We further characterize magnetic domains and grainy stray magnetic fields in the nanomagnets and their halo side-deposits. The published work may aid in the evaluation of such nanomagnets for applications in spin qubits, magnetic field sensing, and magnetic logic.

The research was carried out by Ph.D. student Liza Žaper and the project was led by research scientist Dr. Floris Braakman. Research scientist Dr. Boris Groß helped with magnetic simulations. The work also benefitted from close collaborations with Dr. Peter Rickhaus (Qnami), Dr. Marcus Wyss (Nano Imaging Lab, Swiss Nanoscience Institute), and Dr. Kai Wagner (Maletinsky group, Department of Physics, University of Basel).

Swiss Quantum Days

From the 31st to February 1st, Prof. Poggio attended the first two days of the second edition of the Swiss Quantum Days in Villars-sur-Ollon, Switzerland. The conference focused on quantum materials, quantum sensing, quantum information, and quantum computation and included a number of prominent researchers in the field based in Switzerland.

Group Members at Nano in the Snow

From the 17th to the 19th, Ph.D. students Lukas Schneider, Luca Forrer, Mathias Claus, and Prof. Poggio attended this year’s edition of Nanoscience in the Snow, which was held at the Hotel Mont Paisible in Crans-Montana, Switzerland. Each presented a poster and Prof. Poggio gave a talk entitled, “Using nanomechanics to study nanomagnetism”.

Joe Wilcox Visits

From the 9th to the 11th, Dr. Joe Wilcox from the University of Bath, UK visited our group. Joe is an experimental physicist working on understanding the fundamental physics of unconventional superconductivity in the group of Prof. Simon Bending. Post-doctoral researcher Dr. Estefani Marchiori and Ph.D. student Lukas Schneider have started a collaboration with Joe.