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Journal Article

Quadrupole spin polarization as signature of second-order topological superconductors

MPS-Authors
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Kennes,  D. M.
Institut für Theorie der Statistischen Physik, RWTH Aachen;
Theory Group, Theory Department, Max Planck Institute for the Structure and Dynamics of Matter, Max Planck Society;

Fulltext (public)

PhysRevB.103.L041401.pdf
(Publisher version), 2MB

Supplementary Material (public)

SM.pdf
(Supplementary material), 2MB

Citation

Plekhanov, K., Müller, N., Volpez, Y., Kennes, D. M., Schoeller, H., Loss, D., et al. (2021). Quadrupole spin polarization as signature of second-order topological superconductors. Physical Review B, 103(4): L041401. doi:10.1103/PhysRevB.103.L041401.


Cite as: http://hdl.handle.net/21.11116/0000-0007-CFAC-F
Abstract
We study theoretically second-order topological superconductors characterized by the presence of pairs of zero-energy Majorana corner states. We uncover a quadrupole spin polarization at the system edges that provides a striking signature to identify topological phases, thereby complementing standard approaches based on zero-bias conductance peaks due to Majorana corner states. We consider two different classes of second-order topological superconductors with broken time-reversal symmetry and show that both classes are characterized by a quadrupolar structure of the spin polarization that disappears as the system passes through the topological phase transition. This feature can be accessed experimentally using spin-polarized scanning tunneling microscopes. We study different models hosting second-order topological phases, both analytically and numerically, and using Keldysh techniques we provide numerical simulations of the spin-polarized currents probed by scanning tips.