Paweł Szumniak (27.02, 16:30)
Affiliation: AGH University of Science and Technology Title: Spin and Charge Signatures of Topological Superconductivity in Rashba Nanowires Abstract:Topological phases of condensed matter systems have attracted a lot of attention over many years. One of the hallmarks of such phases, in particular of topological superconductivity, are Majorana fermions which are promising candidates for topological quantum computing [1]. As a result, most of the theoretical and experimental work so far has focused on such Majorana modes [2] and their detection. However, this has turned out to be a very challenging task, especially for experimentalists searching for them [3], since the unambiguous identification of Majorana fermions (typically via transport data) is not easy and often even meet with controversy due to masking effects e.g. from disorder or Kondo physics. Thus, it is of great interest and importance to look for alternative signatures of topological phases that are not relying on the presence or absence of Majorana fermions but test the topological superconductivity itself. Here, we show that the topological phase of a proximitized Rashba nanowire can be identified via the bulk properties of the states, in particular, by the spin and charge of low-energy bulk states close to the topological gap. Quite remarkably, we find that the sign of the spin component along the magnetic field as well as of charge of these low-energy states reverses as the system passes through the topological phase transition [4]. This sign reversal is a direct consequence of the band inversion and is directly accessible in experiments by spin and energy resolved measurements. We show that proposed new signature is highly robust to the static onsite and magnetic disorder. We suggest experimental method for detecting spin inversion assisted with topological phase transition by employing quantum dot acting as a spin filter [5]. Our predictions thus provide an entirely novel approach in the search for topological superconductivity, which is complementary to Majorana one. [1] A. Y. Kitaev, Ann. Phys. 303, 2 (2003).
[2] L. Fu and C. L. Kane, Phys. Rev. Lett. 100, 096407 (2008).
[3] V. Mourik, K. Zuo, S. M. Frolov, S. R. Plissard, E. P. A. M. Bakkers, and L. P. Kouwenhoven, Science 336, 1003 (2012).
[4] P. Szumniak, D. Chevallier, J. Klinovaja, and D. Loss, Phys. Rev. B 96, 041401(R), (2017).
[5] D. Chevallier, P. Szumniak, S. Hoffman, D. Loss, and J. Klinovaja, Phys. Rev. B 97, 045404 (2018).