electron spin and GaAs nuclear spin; nuclear magnetism; electron interactions; quantum coherence; persistent spin helix; mesoscopic physics; nanoscience; experimental condensed matter physics
Friedl Martin, Cerveny Kris, Weigele Pirmin, Tütüncüoglu Gozde, Martí-Sánchez Sara, Huang Chunyi, Patlatiuk Taras, Potts Heidi, Sun Zhiyuan, Hill Megan O., Güniat Lucas, Kim Wonjong, Zamani Mahdi, Dubrovskii Vladimir G., Arbiol Jordi, Lauhon Lincoln J., Zumbühl Dominik M., Fontcuberta i Morral Anna (2018), Template-Assisted Scalable Nanowire Networks, in Nano Letters
, 18(4), 2666-2671.
Palma M., Scheller C. P., Maradan D., Feshchenko A. V., Meschke M., Zumbühl D. M. (2017), On-and-off chip cooling of a Coulomb blockade thermometer down to 2.8 mK, in Applied Physics Letters
, 111(25), 253105-253105.
Hug D., Zihlmann S., Rehmann M. K., Kalyoncu Y. B., Camenzind T. N., Marot L., Watanabe K., Taniguchi T., Zumbühl D. M. (2017), Anisotropic etching of graphite and graphene in a remote hydrogen plasma, in npj 2D Materials and Applications
, 1(1), 21-21.
Dettwiler Florian, Fu Jiyong, Mack Shawn, Weigele Pirmin J., Egues J. Carlos, Awschalom David D., Zumbühl Dominik M. (2017), Stretchable Persistent Spin Helices in GaAs Quantum Wells, in Physical Review X
, 7(3), 031010-031010.
Palma M., Maradan D., Casparis L., Liu T.-M., Froning F. N. M., Zumbühl D. M. (2017), Magnetic cooling for microkelvin nanoelectronics on a cryofree platform, in Review of Scientific Instruments
, 88(4), 043902-043902.
This proposal consists of three projects, outlined below: helical electron and nuclear spin order, spin-orbit coupling in low-dimensional systems, and fundamental processes in quantum dots.We have recently published first evidence for helical nuclear spin order in GaAs cleaved edge overgrowth wires -- a successful outcome of the predecessor of this proposal. But this was only the first step, many questions are open. Here, we propose to use double-wire tunneling spectroscopy, finite-size interference fringes and thermo-power experiments (among others) to shead independent, additional light on the this system.Tunneling spectroscopy can extract the electronic dispersion, which is predicted to reflect the nuclear helix: a spin-selective gap at the Fermi energy in half of the modes. Further, in collaboration with the Wegscheider group (ETH Zurich), we will grow new wires. This is a very challenging task, but with a large pay-off, giving access also to single wires, multi mode systems and side gates -- all very useful.The spin-orbit (SO) interaction is the preeminent mechanism governing the physics of spins in semiconductors and thus plays a crucial role in spintronics and quantum computation. Recently, we have demonstrated unprecedented command over the SO parameters in GaAs quantum wells -- another successful outcome of the predecessor proposal. Now, we propose to apply this technique to confined geometries in nanostructures, where control of the SO interaction is essential. In quantum dots, SO control gives access to longer spin relaxation times, allows investigation of an unresolved decoherence problem, and gives a much better approach to study the physics of the singlet-triplet avoided crossing in two electron dots.For this, the GaAs quantum well material might have to be improved in terms of mobility and charge stability. Further, systems with much stronger SO coupling than GaAs are also of great interest for helical and topological states of matter including Majorana fermions and parafermions. Here, we propose to investigate InAs structures in both 2D and 1D, working closely with the Fontcuberta group (EPF Lausanne) and Wegscheider group (ETH Zurich).Finally, we propose to study a number of fundamental processes in quantum dots: a thermally activated charge instability, causing both spin and charge relaxation, the interplay between the spin-orbit and hyperfine interaction, the spin tunneling asymmetry, and the spin relaxation process, including its magnetic field asymmetry. In dots with in-situ controllable spin-orbit coupling, the spin relaxation rate can be extended considerably.If GaAs quantum dots are going to be used as the elementary building blocks for future quantum information processing, then it is crucial that these fundamental effects are well understood and under check, since they can severely limit operation, particularly when scaling to a larger number of quibts.