Two Founding Ph.D. Students Move On

After short stays in the group following their graduations, both Dr. Michele Montinaro and Dr. Dennis Weber will be moving on to promising new jobs in 2015. Michele will take a position at Sensirion AG in Stäfa, Switzerland and Dennis will teach science and mathematics in the Basel school system. As the second and third Ph.D. students in the group, both Michele and Dennis were crucial to building up or lab and setting the foundations for the group as it is today. The lab will miss both of them and we wish them the best of luck in all their future pursuits!

Seminar at Max Planck Institute for Solid-state Research

Prof. Poggio travelled to the Max Planck Institute for Solid-state Research in Stuttgart on the 17th on the invitation of Dr. Markus Ternes.  There he visited the laboratories and gave the weekly seminar at the Nanoscale Science Department of Prof. Klaus Kern.

Group Members Star in SNI Video

Several of our group members make appearances in a new Swiss Nanoscience Institute (SNI) video on the Masters and Ph.D. programs in nanoscience here at the University of Basel. Ph.D. students Davide Cadeddu, Marcus Wyss, Arne Buchter, Benedikt Herzog, Dr. Floris Braakman, and Prof. Poggio all appear somewhere in the 6-minute video. The section showing our lab starts at the 4:10 mark.

End of the Year Parties

To celebrate the end of another successful year, the group had two holiday parties. The first, on Monday the 8th, was a dinner at Zum Isaak on Münsterplatz together with members of the Maletinsky and Warburton Groups. Thanks to Ph.D. student Arne Barfuss of the Maletinsky group for organizing. The second, on Friday the 12th, was a late lunch for our own group members at Restaurant Gifthüttli near Marktplatz. Thanks to Dr. Dennis Weber for organizing. Happy holidays to everyone and let’s look forward to another great year in 2015!

Ph.D. Student in Rome

Ph.D. student Marcus Wyss attended the Magnetism at Large Scale Facilities conference in Rome from the 25th to the 26th. The aim of the conference, promoted by the Italian Magnetism Association (AIMagn) and organized  in collaboration with the Institute of Structure of Matter (ISM) of the National Research Council (CNR), is to present and discuss recent experiments on magnetism performed using large scale facilities such as  the synchrotrons, free electron lasers, neutron or muons sources, and high magnetic field facilities.

APL on Nonlinear Mechanics in Nanowires Published

Our paper entitled, Nonlinear motion and mechanical mixing in as-grown GaAs nanowires, was published on October 30th in the “Nanoscale Science and Technology” section of Applied Physics Letters. In the manuscript, we report on nonlinear behavior in the motion of driven nanowire cantilevers. The nonlinearity can be described by the Duffing equation and is used to demonstrate mechanical mixing of two distinct excitation frequencies. Furthermore, we demonstrate that the nonlinearity can be used to amplify a signal at a frequency close to the mechanical resonance of the nanowire oscillator. Up to 26 dB of amplitude gain is demonstrated in this way. Dr. Floris Braakman and Ph.D. student Davide Cadeddu led the experiments in our lab. The GaAs nanowires were grown by our collaborators in the Fontcuberta Group at the EPFL.

Prof. Poggio at Quantum Technologies Workshop

Prof. Poggio gave a talk at the Quantum Technologies: Hybrid Emitter – Solid State Systems workshop in Strasbourg, France. The talk was entitled, “Quantum dot opto-mechanics in a fully self-assembled nanowire”, and took place on Wednesday, September 24th. On Thursday the 25th, Prof. Poggio also gave a longer talk at the associated graduate school, entitled, “Nanomechanics and Spin in Solid-state Systems”.

Third Ph.D. Student Graduates

On the 19th of September, Ph.D. student Dennis Weber defended his thesis and earned his physics doctorate magna cum laude. The examination was chaired by Prof. Christoph Bruder with Prof. Poggio and Prof. Ernst Meyer making up the committee. Dennis joined the lab in September of 2009 and his graduation signifies the end of an era, as each of the first generation members of the Poggio Lab (Phani, Michele, Dennis, and Fei) have now graduated or moved on. Dennis, like his colleagues, met the challenge of starting work in an empty lab and went on to publish his work in prestigious journals. Congratulations to Dr. Weber, we will miss you, and good luck for the future from everyone in the lab!

Physik I für Biologen Starts

Together with Prof. Thomas Jung, Prof. Poggio is teaching “Physik I für Studierende der Biologie, Geowissenschaften und Pharmazeutische Wissenschaften” this semester. This is Prof. Poggio’s first lecture in German and covers the basics of mechanics, fluid dynamics, and thermodynamics for non-physics science bachelor students. The first lecture of the semester is on September 18th.

Second Ph.D. Student Graduates

Ph.D. student Michele Montinaro defended his thesis on the 17th of September earning his physics doctorate summa cum laude. Prof. Richard Warburton presided over the examination with Prof. Poggio and Dr. Heike Reil (IBM Zürich) making up the committee. Michele is the second student from the Poggio Lab to complete his Ph.D. having joined the group in May 2009 when the lab was still empty. Despite the challenges associated with starting in an empty lab, Michele was able to carry out top-notch research and publish in prestigious journals along the way. Congratulations to Dr. Montinaro and good luck to him in the future from everyone in the lab!

Post-doc Starts Work in the Lab

Dr. Boris Groß starts work in the lab in mid-September. Boris earned his Ph.D. in Physics from the University of Tübingen in 2013. Most recently he worked as a post-doc in Tübingen continuing his studies of terahertz radiation generated by Josephson junctions in the high transition superconductor Bi₂Sr₂CaCu₂O_8+δ.

Group Trip to Celerina

On the weekend of September 13th, we made our 2nd group trip to the high-mountain town of Celerina in the Canton Graubünden. Group members enjoyed hiking, cooking, eating, and some excellent weather. Thanks to everyone on the trip for a good time!

SNI Meeting in Lenzerheide

Prof. Poggio and Ph.D. student Davde Caddedu attended the Annual Meeting of the Swiss Nanoscience Institue (SNI) in Lenzerheide, Switzerland. Davide presented a poster.

Farewell Dinner for Audrey Fischer

On Wednesday September 10th,  the group had a farewell dinner in honor of Audrey Fischer.  Audrey, who worked on behalf of our group on all administrative and budgeting matters, is starting a new job in the Chemistry Department. We wish her well and are happy that she will not be moving too far away!

Nuclear Magnetic Resonance in a Single Quantum Dot

Our collaborators in the Warburton Group, published a paper in Nature Nanotechnology entitled, Manipulation of the nuclear spin ensemble in a quantum dot with chirped magnetic resonance pulses, on August 24th. The paper describes nuclear magnetic resonance (NMR) experiments on nuclear spins within a single quantum dot using chirped radiofrequency (RF) pulses. The experiments represent a generic technique for manipulating nanoscale inhomogeneous nuclear spin ensembles and open the way to probe the coherence of such mesoscopic systems. Our group collaborated on the project led by Frof. Warburton. Former group member Dr. Fei Xue designed the RF mircowire and provided critical expertise in its fabrication. Dr. Xue and Prof. Poggio also guided the design of the NMR pulses.

Group Members at Nanowires 2014

Post-doc Floris Braakman and Ph.D. student Davide Cadeddu attended the 8th Nanowire Growth Workshop (Nanowires 2014) in Eindhoven.  Davide gave a talk on recent work entitled,  “Nonlinear Motion and Mechanical Mixing in As-grown Nanowires”, which won a prize as the best talk.

Talks at ICPS and Condensed Matter in Paris

Ph.D. student Michele Montinaro gave talks on his work at two recent conferences: The 32nd International Conference on the Physics of Semiconductors (ICPS) in Austin and Condensed Matter in Paris 2014 (JMC 14, CMD 25). Michele discussed his experiments on optically active quantum dots (QDs) embedded in MBE-grown GaAs/AlGaAs core–shell nanowires (NWs). The research was recently published in the journal Nano Letters under the title, Quantum dot opto-mechanics in fully self-assembled nanowire.

Machine Shop / Poggio Lab Summer Barbeque

On August 22nd together with our friends in the Physics Department Machine Shop, we organized our annual summer barbeque. Thanks to everyone who helped make the event a success. The weather was great and lots of fun was had by all. See you again next year!

Statistical Polarization Paper Appears in APL

Our paper entitled, Boundary between the thermal and statistical polarization regimes in a nuclear spin ensemble, was published in the “Nanoscale Science and Technology” section of Applied Physics Letters on August 1st. In the manuscript, we present measurements of nanometer-scale ensembles of nuclear spins in a KPF₆ sample using magnetic resonance force microscopy. In particular, we investigate the transition between regimes dominated by thermal and statistical nuclear polarization. The ratio between the two types of polarization provides a measure of the number of spins in the detected ensemble. Ph.D. student Ben Herzog led the experiments with significant contributions from Ph.D. student Davide Cadeddu. Futher contributions came from Poggio Lab alumni Dr. Fei Xue and Dr. Phani Peddibhotla.

Quantum Dot Opto-mechanics Paper Published

On July 7th, our paper entitled, Quantum dot opto-mechanics in a fully self-assembled nanowire, was published in Nano Letters. In the paper we show that optically active quantum dots (QDs) embedded in MBE-grown GaAs/AlGaAs core–shell nanowires (NWs) are coupled to the NW mechanical motion by material strain. Oscillations of the NW modulate the QD emission energy in a broad range exceeding 14 meV. Furthermore, this opto-mechanical interaction enables the dynamical tuning of two neighboring QDs into resonance, possibly allowing for emitter–emitter coupling. Both the QDs and the coupling mechanism are intrinsic to the NW structure and do not depend on any functionalization or external field. Such systems open up the prospect of using QDs to probe and control the mechanical state of a NW, or conversely of making a quantum nondemolition readout of a QD state through a position measurement. The experiments were led by Ph.D. student Michele Montinaro here in Basel in close collaboration with Gunter Wüst and Mathieu Munsch from the group of Prof. Richard Warburton in Basel and Yannik Fontana from the group of Prof. Anna Foncuberta at EPFL. The NWs were grown in the Foncuberta group.

NEMS 2014 Conference in Paris

Prof. Poggio attended the International Seminar on Nanomechanical Systems, NEMS 2014, from June 30th to July 2nd in Paris. There he gave a talk entitled, “Cantilever magnetometry of nano-magnetic systems”, on Monday afternoon.

Ph.D. Student Starts Work

Ph.D. student Nicola Rossi starts work in the lab this month. Nicola received his Bachelor of Science in 2010 and his Masters degree in 2013 both in Electrical Engineering from the University of Genova, Italy.

Lunch Seminar at ETH Zürich

On Thursday June 5th, Ph.D. student Benedikt Herzog gave a talk at the ETH Zürich entitled, “Boundary between the Thermal and Statistical Polarization Regimes in a Nanometer-scale Spin Ensemble”. Ben was invited to give the talk as part of the weekly QSIT Lunch Seminar at ETH and took the opportunity to present his latest experimental results using magnetic resonance force microscopy (MRFM).

Magnetometry APL Published

On May 7th, our paper entitled, Vortex lattice melting of a NbSe2 single grain probed by ultrasensitive cantilever magnetometry was published in the “Superconductivity and Superconducting Electronics” section of Applied Physics Letters. The paper discusses a research project led by Ph.D. student Lucia Bossoni of the University of Pavia and the Univeristy of Roma Tre. The experiments were conducted during her visits to our lab here in Basel. The project was realized in close collaboration with Lucia’s Ph.D. advisor, Prof. Pietro Carretta of the University of Pavia.

Farewell Lunch for Dr. Hari Solanki

On Monday, April 28th the group held a farewell lunch for our second post-doc, Dr. Hari Solanki in Klein Basel. Hari, part of the group since August 2011, led our first efforts to measure self-assembled nanowires. In so doing, he set up and developed a number of complex processes and measurement protocols. Having secured a post doctoral position at the prestigious London Centre for Nanotechnology, Hari has decided to accept it. While we are sad to lose him, we wish Hari the best of luck in his new adventure in London. We look forward to continuing to work with Hari on the various projects that he started here in Basel. Thanks for everything, Hari, and good luck!

Prof. Poggio in California

Prof. Poggio travelled to California on April 21st for the 2014 Materials Reserch Society (MRS) Spring Meeting in San Francisco. There he was a co-organizer of a symposium on April 22nd entitled, Few-Dopant Semiconductor Optoelectronics, along with Prof. Michael Flatté, Prof. David Awschalom, and Prof. Michelle Simmons. On April 23rd, he visited Dr. Dan Rugar and Dr. John Mamin at the IBM Almaden Research Center in San Jose. Finally he stopped in Santa Barbara on the invitation of Prof. Ania Bleszynski Jayich for a seminar on April 24th and a visit of colleagues at the UCSB Physics Department.

Student Speaks at Skymag Conference

Ph.D. student Andrea Mehlin gave a talk at Skymag 2014 in Paris on Thursday, April 10th. The conference, hosted on the campus of Chimie ParisTech in the heart of Paris, featured invited talks by prominent physicists in the emerging field of magnetic Skyrmions. The program also included talks about recent results and a poster session. Andrea spoke about our recent experiments, in which we use cantilever magnetometry to measure the skyrmion phase in MnSi nanowires. Prof. Poggio was also in attendance on Thursday.

Ph.D. Student Starts in the Lab

On April 1st, Marcus Wyss started work as a Ph.D. student in our group. Marcus received both his Bachelor and Masters degrees in Nanoscience from the University of Basel. He completed his Masters project at the Paul Scherrer Institute on artificial spin ice under the supervision of Prof. Dr. Laura Jane Heyderman in the lab of Prof. Dr. Frithjof Nolting.

55th ENC Conference in Boston

On Friday March 28th Prof. Poggio gave an invited talk at the 55th annual Experimental Nuclear Magnetic Resonance Conference (ENC) in Boston. The talk entitled, “Harnessing nuclear spin polarization fluctuations in a semiconductor nanowire”, was part of the last session of the conference: “Sensitivity, Resolution, Alternative Detection: Pushing the Boundaries”.

2nd Nano-magnetism Workshop

On March 12th and 13th our group took part in a workshop on nano-magnetism organized by Prof. Anna Fontcuberta i Morral. The workshop took place at the Laboratory of Semiconductor Materials (LMSC) on the campus of EPFL and included members from our group, Prof. Fontcuberta’s group, Prof. Dirk Grundler’s group (TUM), and Prof. Dieter Kölle’s group (Tübingen). The first edition of the workshop took place in Basel in October 2012. This year, the topics of discussion were expanded to include nanowire heterostructures and nanomechanics. Students and post-docs gave short talks aimed at generating discussion and expanding ongoing collaborations between the groups. We thank Prof. Fontcuberta and all of the participants for their contributions to a successful event.

Post-Doc Starts Work

Dr. Denis Vasyukov starts work in the lab in late February. Denis earned his Ph.D. in Physics in 2009 from the University of Exeter, UK going on to work as a post-doc at the Weizmann Institute of Science and most recently as a research fellow at the National Univeristy of Singapore. His position is funded by our new ERC Starting Grant.

Fundamental Digital Electronics Begins

Prof. Poggio’s course entitled Fundamental Digital Electronics is now underway. Lectures will be Tuesdays, 10.00-12.00 in Neuer Hörsaal 1. On weeks requiring practical labs, there will be a lab session Wednesdays 13:00-14:00 in Seminarzimmer 2.04. On weeks requiring written exercises, there will be an exercise session Wednesdays, 13:00-14:00 in 4.1.

QSIT Meeting in Arosa

During the first week of February, Ph.D. students Ben Herzog and Michele Montinaro, Dr. Floris Braakman, and Prof. Poggio attended the 4th NCCR QSIT General Meeting in Arosa, Switzerland. Ben Herzog also participated in the QSIT school before the meeting. Michele gave a talk at the meeting entitled, “Quantum dot opto-mechanics in a fully self-assembled nanowire”, Ben presented a poster, and Prof. Poggio was persuaded to contribute to the Rump Session. Many thanks to QSIT director Prof. Klaus Ensslin, co-director Prof. Richard Warburton, and especially QSIT coordinator Ilona Blatter for putting on a great conference!

Nano in the Snow

From January 29 to 31st, Ph.D. student Davide Cadeddu attended this year’s SNI Winter school — known as “Nanoscience in the Snow 2014″ — in Kandersteg, Switzerland. Thanks to Audrey Fischer and Michele Calamé for oganizing the meeting!

Degen Lab PhD Visit

Ph.D. student Urs Grob from Prof. Christian Degen‘s lab at the ETH Zürich visited our group at the end of January. Urs has been working with our two groups’ shared post-doctoral researcher, Dr. Paolo Navaretti on fabricating the next generation of ultrasensitive Si cantilevers. In our lab, he made use of our room-temperature UHV chamber for the mechanical characterization of his latest devices. Ph.D. student Ben Herzog trained Urs on all of the relevant equipment. We look forward to more visits from Urs in the near future.