Bakgrunn og aktiviteter

Forskning:

My research at NTNU will focus on growth of single crystalline materials by molecular beam epitaxy (MBE). In particular, materials with antiferromagnetic and superconducting properties will be grown. These materials will be investigated by electronic transport studies at low temperatures (in the range of a few °K).

Molecular beam epitaxy is a technique used for the growth of ultrapure crystals in the form of thin films or nanostructures (e.g. nanowires and quantum dots). MBE growth allows for a large amount of control on the properties of a material, especially, the dimensions, interfaces and strain of a material can be controlled very precisely. MBE growth also enables the combination of materials into heterostructures and superlattices, where the individual materials can be stacked in thicknesses of a few nanometers or less, down to single atomic layers. In this way, the (quantum mechanical) properties of a material can be influenced to custom-tailor materials with specific behavior or to access new physical phenomena.

Quantum transport studies can be used to gain insight into the electrical response of nanostructures and low dimensional systems. In electrical transport studies, properties like material resistance, response to electric fields and the flow of electrical currents are investigated in a system. Usually, it is necessary to go to very low temperatures to access the quantum mechanical effects in a system, therefore most transport studies are carried out in cryostats, which allow measurements down to temperatures of a few milli-Kelvin, close to absolute zero.

 

Utvalgte publikasjoner:

  • Bocquillon, E., et al., "Gapless Andreev bound states in the quantum spin Hall insulator HgTe." Nature Nanotechnology 12(2): 137-143. (2017) 
  • Deacon, R. S., et al., "Josephson Radiation from Gapless Andreev Bound States in HgTe-Based Topological Junctions." Physical Review X 7(2). (2017)
  • Dziom, V., et al., "Observation of the universal magnetoelectric effect in a 3D topological insulator." Nature Communications 8. (2017)
  • Hart, S., et al., "Controlled finite momentum pairing and spatially varying order parameter in proximitized HgTe quantum wells." Nature Physics 13(1): 87-93. (2017)
  • Leubner, P., et al., "Strain Engineering of the Band Gap of HgTe Quantum Wells Using Superlattice Virtual Substrates." Physical Review Letters 117(8). (2016)
  • Wiedenmann, J., et al., "4 pi-periodic Josephson supercurrent in HgTe-based topological Josephson junctions." Nature Communications 7. (2016)
  • Ma, E. et al., "Unexpected edge conduction in mercury telluride quantum wells under broken time-reversal symmetry." Nature Communications 6. (2015)
  • Sochnikov, I., et al., "Nonsinusoidal Current-Phase Relationship in Josephson Junctions from the 3D Topological Insulator HgTe." Physical Review Letters 114(6). (2015)
  • Brüne, C.,et al.,  "Dirac-Screening Stabilized Surface-State Transport in a Topological Insulator." Physical Review X 4(4). (2014)
  • Hart, S., et al., "Induced superconductivity in the quantum spin Hall edge." Nature Physics 10(9): 638-643. (2014)
  • Nowack, K. C., et al., "Imaging currents in HgTe quantum wells in the quantum spin Hall regime." Nature Materials 12(9): 787-791. (2013)
  • Oostinga, J. B., et al., "Josephson Supercurrent through the Topological Surface States of Strained Bulk HgTe." Physical Review X 3(2).  (2013)
  • Brüne, C., et al., "Spin polarization of the quantum spin Hall edge states." Nature Physics 8(6): 485-490. (2012)
  • Brüne, C., et al., "Quantum Hall Effect from the Topological Surface States of Strained Bulk HgTe." Physical Review Letters 106(12). (2011)
  • Büttner, B., et al., "Single valley Dirac fermions in zero-gap HgTe quantum wells." Nature Physics 7(5): 418-422. (2011)
  • Shuvaev, A. M., et al., "Giant Magneto-Optical Faraday Effect in HgTe Thin Films in the Terahertz Spectral Range." Physical Review Letters 106(10). (2011)
  • Brüne, C., et al., "Evidence for the ballistic intrinsic spin Hall effect in HgTe nanostructures." Nature Physics 6(6): 448-454. (2010)
  • Roth, A., et al., "Nonlocal Transport in the Quantum Spin Hall State." Science 325(5938): 294-297. (2009)
  • König, M., et al., "Quantum spin hall insulator state in HgTe quantum wells." Science 318(5851): 766-770. (2007)

 

Invited Talks

  • 2018 MRS Spring Meeting, Phoenix, USA - invited talk, 2018.
  • RACIRI Summer School 2017, Ronneby, Sweden - invited talk 2017.
  • Seminar of the condensed matter institute, TU Vienna, Austria - invited seminar talk, 2017.
  • Seminar of the International Center for Nanosystems and the Max Plank Institute of Microstructure Physics, Halle, Germany - invited seminar talk, 2017.
  • Workshop on Scientific Directions for Future Transmission Electron Microscopy, Jülich, Germany - invited speaker, 2016.
  • SPICE Young Research Leaders Workshop, Mainz, Germany - invited speaker, 2016 
  • International Conference on Molecular Beam Epitaxy 2016, Montpellier, France - plenary speaker, 2016. 
  • 20th German-American Symposium by the Kavli Foundation and the Humbolt Foundation, Potsdam, Germany - invited speaker, 2016. 
  • Workshop Quantum Matter and Quantum Devices, Delft, Netherlands - invited speaker, 2015.
  • SpinTech 8, Basel,Switzerland - invited speaker, 2015.
  • International Conference on Magnetism, Barcelona, Spain - invited speaker, 2015.
  • European Materials Research Society Fall Meeting, Warsaw, Poland - invited speaker, 2014.
  • Topology and Nonequilibrium in Low-Dimensional Electronic Systems workshop, Dresden, Germany - invited speaker, 2013.
  • Newspin 3, Mainz, Germany - invited speaker, 2013.
  • Narrow Gap Semiconductors and Systems - NGS-16, Hangzhou, China - invited speaker, 2013.
  • DPG Frühjahrstagung, Regensburg, Germany - invited speaker, 2013.
  • Workshop on Spectroscopy of Novel Materials, Beatenberg, Switzerland - invited speaker, 2012.
  • Workshop Nanopeter 2012, St. Petersburg, Russia - invited speaker, 2012.
  • Seminar at the institute for physics at Karlsruhe Institue for Technology, Karlsruhe, Germany - invited seminar speaker, 2012.
  • IOP Workshop on Frontiers of Dirac Electron Systems, Beijing, China - invited speaker, 2012.
  • II-VI workshop, Seattle, USA - invited speaker, 2012.
  • Seminar talk at IBM Almaden, group of Steward Parkin, IBM Almaden-San Jose, United states - invited seminar talk, 2012.
  • High Magnetic Fields in Semiconductor Physics, HMF-20, Chamonix-Mont-Blanc, France - invited speaker, 2012.
  • CECAM workshop Topological Materials, Bremen, Germany - invited speaker, 2012.
  • 3rd EuroMagNET Summer School - Science in High Magnetic Fields, Rügen, Germany invited lecture, 2012.
  • Tweedaagse van de Theoretische en Mathematische Fysica workshop, Domein Westhoek, Belgium - invited speaker, 2011.
  • Seminar at the Institute for Theoretical Physics, Universität Köln, Germany - invited seminar talk, 2011.
  • European Materials Research Society Fall Meeting, Warsaw, Poland invited speaker, 2011.
  • Workshop on Interactions, Disorder, and Topology in Quantum Hall Systems, Dresden, Germany - invited speaker, 2010.
  • SpinAge 2010, Watsonville California, USA - invited speaker, 2010.
  • International Conference on Molecular Beam Epitaxy 2010, Berlin, Germany - invited speaker, 2010.