Prof. Pierre Verlot of the University of Lyon visited our group from the 12th to the 14th. He was joined by Dr. Alexandros Tavernarakis of the Institute of Photonic Sciences (ICFO) in Barcelona for discussions on recent experiments and potential collaborations. Prof. Verlot also gave a talk on the 12th at our Department’s Nano and Quantum Physics Seminar entitled, “Opto/electromechanics with Extremely Small Mechanical Resonators: Novel Challenges & Perspectives”.
Our new ‘Block Course’ entitled, “Measurement, Control, & Acquisition” started for students of the Nanoscience Curriculum. Dr. Floris Braakman, Dr. Boris Gross, and Ph.D. student Thibaud Ruelle developed the course from scratch and took responsibility for the teaching. The course takes a look at problems in data acquisition and measurement control using modern and widely available micro-controllers.
The November issue of APS News highlighted our work on nanowire AFM sensors on its front page. The highlighted article is entitled, Vectorial scanning force microcopy using a nanowire sensor, and represents one of our ongoing investigations on how to take advantage of nanowires as sensitive scanning sensors.
On the 10th and 11th, Prof. Poggio attended the German-Japanese Meeting on the Science of Hybrid Quantum Systems in Berlin, Germany. The objective of the workshop was to bring together experts in different fields with the ultimate goal of establishing new ideas for future quantum hybrid systems. The event joined experts from Japan and Europe and was supported by the Japanese initiative, “Science of Hybrid Quantum Systems”, as well as by the Paul-Drude-Institut für Festkörperelektronik (PDI), in Berlin. On the evening of the 10th, Prof. Poggio gave an invited talk entitled, “Nanowire Hybrid Systems and Sensors”. Thanks to the organizers for a stimulating and well-organized workshop.
On the 28th, Physics, the APS’s daily news and commentary site, named our work on nanowire AFM sensors as an Editors’ Choice. The story highlighted our article entitled, Vectorial scanning force microcopy using a nanowire sensor along with related work.
On the 18th, the Neue Zürcher Zeitung published a piece highlighting our work using nanowires as sensors for atomic force microscopy. The story is based on our article entitled, Vectorial scanning force microcopy using a nanowire sensor, published in Nature Nanotechnology. A follow-up version of the story appeared in the Friday, 21 October 2016 print edition of the paper on page 59.
On Monday, the 17th, Nature Nanotechnology published our article entitled, Vectorial scanning force microcopy using a nanowire sensor, in which we demonstrate a new type of atomic force microscope (AFM) using nanowires (NWs) as tiny sensors. Unlike standard AFM, the NW-based technique enables measurements of both the size and direction of forces.
Self-assembled NW crystals can be grown into nearly defect-free nanomechanical resonators with exceptional properties, including small motional mass, high resonant frequency and low dissipation. Furthermore, by virtue of slight asymmetries in geometry, a NW’s flexural modes are split into doublets oscillating along orthogonal axes. These characteristics make bottom-up grown NWs extremely sensitive vectorial force sensors. Taking advantage of its adaptability as a scanning probe, we demonstrate the use of a single NW to image a sample surface. By monitoring the frequency shift and direction of oscillation of both modes as we scan above the surface, we construct a map of all spatial tip–sample force derivatives in the plane. Finally, we use the NW to image electric force fields distinguishing between forces arising from the NW charge and polarizability. This universally applicable technique enables a form of atomic force microscopy particularly suited to mapping the size and direction of weak tip–sample forces.
The work represents a collaboration between our group, led by Ph.D. student Nicola Rossi and post-doc Dr. Floris Braakman, and the group of Prof. Anna Fontcuberta i Morral at EPFL. Ph.D. student Davide Cadeddu and Dr. Denis Vasyukov from our group also contributed, while Ph.D. student Gözde Tütüncüoglu from the Fontcuberta group grew the NWs. The study was supported by the European Research Council Starting Grant NWScan, the Swiss Nanoscience Institute, the Canton Aargau, the Swiss National Science Foundation, and the National Center of Competence in Research for Quantum Science and Technology.
More information is available in a news piece by the University of Basel Press Office.
On Thursday, September 22nd the lecture “Physics I for Biologists, Geoscientists, and Pharmaceutical Scientists” began and will run until Friday, December 23rd. The exam is scheduled for February 3rd, 2017, 9:00 – 11:00. The lecture covers the basics of mechanics, fluid dynamics, and thermodynamics for non-physics science bachelor students. Prof. Poggio is giving the lecture together with Prof. Michel Calame.
Post-doc Dr. Floris Braakman attended the 15èmes Journées de la Matière Condensée (JMC15) from the 22nd to the 26th in Bordeaux, France. There he gave a talk entitled, “Vectorial scanning force microscopy using a nanowire mechanical resonator”, on our latest work. The talk was part of a minicolloquium entitled, “Optomechanics: Exploring Physics from the macroscopic down to the nanometric scale”.
From the 23rd to the 25th, Ph.D. student Andrea Mehlin attended the Annual Meeting of the Swiss Physical Society (SPS). This year’s edition, held in Lugano, included a session on the 25th about “Magnetism & Spintronics at the Nanoscale”, in which Andrea gave a talk. Her presentation was entitled, “Dynamic Cantilever Magnetometry on Individual Nanomagnets”.
From the 21st to the 26th, post-doc Dr. Boris Gross and Ph.D. student Marcus Wyss attended the 8th Joint European Magnetic Symposia (JEMS) in Glasgow, UK. On the 25th, Marcus gave a talk entitled, “X-PEEM imaging of global vortex states in ferromagnetic nanotubes”, while on the 26th, Boris gave a talk entitled, “Dynamic cantilever magnetometry on individual magnetic nanoparticles”.
On Friday, August 19th we enjoyed our annual summer barbeque with our colleagues in the Machine Shop. Thanks to everyone who helped organize and clean up. See you next year!
From the 4th to the 8th, Ph.D. student Thibaud Ruelle attended the Summer School on Quantum Nano- and Opto-mechanics at the Institute of Photonic Sciences (ICFO) outside Barcelona, Spain. The school is part of the ICFO Schools on the Frontiers of Light series for Masters and starting Ph.D. students. During this intense week-long experience, the students were exposed to a carefully chosen list of topics representing the cutting-edge of research, with the goal of introducing students to, and helping them target their future research directions. Program topics included: levitated optomechanics, optomechanical crystals, atom-optomechanics, carbon nanotube and graphene mechanics, and optical trapping and manipulation of nanoparticles.
On the 11th, a paper entitled, Role of the electron spin in determining the coherence of the nuclear spins in a quantum dot, appeared in the journal Nature Nanotechnology describing research led by the Warburton group and carried out in collaboration with our group and the Loss group here in Basel. Dr. Gunter Wüst and Dr. Mathieu Munsch from the Warburton group carried out the experiments with our group providing nuclear magnetic resonance expertise. Theoretical work was done by Dr. Franziska Maier of the Loss group, while semiconductor material was engineered and grown by the Wieck group at the Ruhr University in Bochum, Germany. The experiments clarify the mechanism by which an electron spin limits the coherence of lattice nuclear spins within a seminconductor quantum dot. These results are particularly relevant to the development of spin qubits in semiconductors, where such interactions play an important role. The university press office provides further information here.
From the 30th to the 1st of July, the group attended the Swiss Nano Convention in Basel, organized by the Swiss Nanoscience Institute (SNI). Ph.D. students Davide Cadeddu, Marcus Wyss, Nicola Rossi, Lorenzo Ceccarelli, and Masters student Alexander Schwarb all presented posters on their research. Prof. Poggio gave a talk entitled, “Vectorial Scanning Force Microscopy Using a Nanowire Sensor”. The talk was part of the “30 years of AFM” session, chaired by Prof. Ernst Meyer and Prof. Christoph Gerber, who recently won the Kavli Prize in Nanoscience for his joint invention of the AFM.
From the 26th to the 30th, post-doc Dr. Boris Gross and Ph.D. student Andrea Mehlin attended the International Conference on Magnetism and Spintronics known as “Sol-Skymag 2016” in San Sebastian, Spain. Topic discussed included magnetism of nanometer-scale systems, magnetization dynamics and reversal, spin waves, magnetic skyrmions, and applications of magnetic nanostructures. Boris and Andrea both gave a talks on their research entitled, “Magnetic states of individual ferromagnetic nanotubes” and “The use of dynamical cantilever magnetometry for the detection of the skyrmion phase”, respectively.
From the 22nd to the 24th, Ph.D. student Nicola Rossi attended the 13th International Workshop on Nanomechanical Sensing (NMC) in Delft, Netherlands. The conference focused on interdisciplinary research related to nanometer-scale sensors. Topics included: instrumentation, biological sensors, chemical sensors, theoretical modelling of sensors, micro- and nano-fabrication, optomechanics, and novel sensing platforms. Nicola gave a talk in the Nano Instrumentation session on entitled, “Vectorial scanning force microscopy using a nanowire mechanical resonator” on our recent experiments, which are described in our pre-print arXiv:1604.01073.
On the 3rd, Prof. Song Jin from the Department of Chemistry at the University of Wisconsin visited our group. Prof. Jin leads a group working on nanometer-scale materials for solar applications and spintronics applications. Our two groups have a running collaboration on skyrmion containing nanowires. Prof. Jin gave a special seminar in the afternoon entitled, “Detection and Manipulation of Magnetic Skyrmions in Metal Silicide Nanowires”.
On the 25th, Dr. Floris Braakman gave a special seminar entitled, “Vectorial scanning force microscopy using a nanowire mechanical resonator”, at the Department of Physics of the Universität Konstanz. Among other topics, Floris discussed recent experiments done with Ph.D. student Nicola Rossi and described in our pre-print arXiv:1604.01073. Floris was a guest of Prof. Eva Weig and visited her research group during his stay.
On the 19th our group hosted the “Basel Nanomagnetism Workshop” here at the University. Together with the Maletinsky Group and visitors from the Helmholtz Zentrum Dresden Rossendorf, we held discussions, listened to talks, and planned future collaborations in the area of nanomagnetics. In the evening we gathered for a dinner at the Atelier in the Hotel Teufelhof. Thanks to all for a successful workshop!
Dr. Cornelia Schwarz from the University of Grenoble and CNRS Grenoble visited our group on Wednesday and Thursday the 30th and 31st. After a welcome dinner on Wednesday evening, she toured our lab facilities and discussed with our group members. She also gave a special seminar to the department entitled, “Optomechanical, vibrational and thermal properties of graphene nanoresonators”.
Thomas Stocker started work in the lab on the 30th. He project will be focused on dynamic cantilever magnetometry of magnetic nanostructures.
Dr. Floris Braakman attended the Gordon Conference on Mechanical Systems in the Quantum Regime from March 6th to 11th in Ventura, California. The conference sought to bring together scientists and engineers across a broad spectrum of fields to discuss ongoing fundamental research and application of mechanical systems exhibiting uniquely quantum phenomena. Floris presented a poster at the meeting.
Prof. Poggio’s course entitled Fundamental Electronics is now underway. Lectures will be on Tuesdays 10:00-12:00 in Neuer Hörsaal 1. Two practical sessions will be held on Tuesday afternoons in Seminarzimmer 3.12: the first 14:00-16:00 and the second 17:00-19:00.
Monday and Tuesday the 22nd and 23rd, Prof. Zeke Johnston-Halperin visited our group and the department. On Monday afternoon he gave a talk entitled, “Something Old is New Again: Semiconductor Spintronics and Dynamically-Driven Spin Currents” at the weekly Nano and Quantum Physics Seminar. Prof. Johnston-Halperin leads a group focusing on spintronics, traditional magnetism, and nanoscale science and materials in the Physics Department of Ohio State University.
On Friday the 19th, nearly 25 among present and former group members and friends went out to dinner at Restaurant Buffet. There was food, beer, wine, and plenty of laughs. Thanks to Ph.D. student Ben Herzog for organizing and to all for another successful year!
On the 5th, Physical Review B published our report on dynamic cantilever magnetometry (DCM) of of ferromagnetic nanotubes entitled, Dynamic cantilever magnetometry of individual CoFeB nanotubes. In the paper we describe experiments on single CoFeB nanotubes with hexagonal cross section. We develop both an analytical model based on the Stoner-Wohlfarth approximation and a broadly applicable numerical framework for analyzing DCM measurements of magnetic nanostructures. Magnetometry data taken at 4.2 K show the presence of a uniformly magnetized configuration at high external fields and nonuniform configurations at low fields. In this low-field regime, comparison between numerical simulations and DCM measurements supports the existence of flux-closure configurations. Crucially, evidence of such configurations is only apparent because of the sensitivity of DCM to single nanotubes, whereas conventional measurements of ensembles are often obscured by sample-to-sample inhomogeneities in size, shape, and orientation. The work represents a collaboration between our group and the groups of Prof. Dirk Grundler (EPFL) and Prof. Anna Fontcuberta i Morral (EPFL), who together produced the ferromagnetic nanotube samples. Former Ph.D. student Dennis Weber led the initial work and carried out the experiments with contributions from former Ph.D. student Arne Buchter. After the experiments, post-doc Dr. Boris Groß took over the project, developing both specialized numerical simulations and refining our understanding of the data.
Between the 1st and the 5th, group members attended the 6th NCCR QSIT General Meeting in Arosa, Switzerland. Ph.D. student Thibaud Ruelle attended both the school and the meeting, while Ph.D. students Nicola Rossi, Davide Cadeddu, Marcus Wyss, post-doc Dr. Floris Braakman, and Prof. Poggio attended the meeting only. Nicola and Marcus presented posters, while Davide gave a talk. Special thanks to Ilona Blatter for organizing another great event!
On the 19th, Nano Letters published our paper entitled, Time-resolved nonlinear coupling between orthogonal flexural modes of a pristine GaAs nanowire. In the report, we demonstrate nonlinear coupling between two orthogonal flexural modes of single as-grown GaAs nanowires. The resonant frequency of one mode can be shifted over many linewidths by mechanically driving the other mode. We present time-domain measurements of the mode coupling and characterize it further by pump-probe experiments. Measurements show that a geometric nonlinearity causes the frequency of one mode to depend directly on the square amplitude of the the other mode. Nearly degenerate orthogonal modes in nanowires are particularly interesting given their potential use in directional force sensing. The research represents a collaboration between our group and the group of Prof. Anna Foncuberta i Morral (EPFL). Ph.D. student Davide Cadeddu and post-doc Dr. Floris Braakman carried out and led the work.
On the 8th, our paper entitled, A fiber-coupled quantum-dot on a photonic tip, was published in Applied Physics Letters. In the manuscript we present the experimental realization of a quantum fiber-pigtail. The device consists of a semiconductor quantum-dot embedded into a conical photonicwire that is directly connected to the core of a fiber-pigtail. We demonstrate a photon collection efficiency at the output of the fiber of 5.8% and suggest realistic improvements for the implementation of a useful device in the context of quantum information. We also discuss potential applications in scanning probe microscopy. The approach is generic and transferable to other materials including diamond and silicon. The research represents a collaboration between researchers from a variety of research groups here in Basel, in Grenoble, and in Denmark. The work grew out of an original idea by Dr. Mathieu Munsch and Dr. Jean Teissier, from the Warburton and Maletinsky Groups respectively. Ph.D. student Davide Cadeddu from our group carried out the experiments and Dr. Munsch led the project. A movie showing the fabrication process can be found here.
This month four new members joined our group, including two Ph.D. students and two Masters students. Alexander Schwarb started work on the 4th as a Masters student in Physics. He will pursue his thesis project within our group working on our nanoSQUID experiments. Thibaud Ruelle began work on the 11th as a Ph.D. student. Thibaud has Bachelors and Masters degrees in Materials Science and Engineering from the Ecole Polytechnique Fédérale de Lausanne an joins Dr. Floris Braakman’s new Ambizione project. Thomas Schefer also joined on the 11th as a Masters student in Nanoscience. Thomas will carry out one of his two project works in our group on cantilever magnetometry. Lorenzo Ceccarelli started his Ph.D. in our group on the 18th and will join our nanoSQUID project. Lorenzo has Bachelors and Masters degrees in Condensed Matter Physics from the University of Bologna. A warm welcome to all!