Topological superconductivity in gold leads to Majorana Zero Mode Pair

Jagadeesh S. Moodera

Surfaces and interfaces play a pivotally defining role for many of the topologically driven nontrivial quantum phenomena. A good example is the prediction of Majorana zero modes (MZMs or the Majorana pair) to occur in a topological superconductor (TSC) – viz., superconducting surface state of gold. [1] A fermion in a TSC can separate in space into two parts known as MZMs. Thus, Majorana pair are Fermionic states, each of which is an antiparticle of itself, and are required to always appear in pair together with its partner. According to the theoretical proposal of Potter and Lee, [1] under the right conditions, a superconducting gold nanowire with (111) crystalline surface with its large Rashba spin-orbit (S-O) splitting could host the Majorana pair. Utilizing the interplay between superconductivity, S-O coupling and Zeeman field we laid the foundation to realize MZM. [2] We have experimentally optimized a novel stable heterostructures, to achieve all these three interactions, to directly observe the MZM pair using a low temperature with high vector field scanning tunneling microscope, by probing the ferromagnetic EuS island over the gold surface. [3] With this two-dimensional stable metal platform, by means of the Shockley surface state (SS) of (111)-gold (Au) with induced superconductivity, we can envision a novel approach to building non-local qubits that are intrinsically fault-tolerant. In this talk I will be presenting our path towards the observation of MZMs.
Supported by John Templeton Foundation Grants No. 39944 and 60148, ONR Grants N00014-16-1-2657, N00014-20-1-2306 and NSF DMR 1700137

[1] A. C. Potter & P. A. Lee PRL 105, 227003 (2010); PRB 85, 094516 (2012)
[2] Peng Wei, Sujit Manna, Marius Eich, Patrick Lee and J. S. Moodera, Phys. Rev. Lett. 122, 247002 (2019)
[3] Sujit Manna, Peng Wei, Yingming Xie, Kam Tuen Law, Patrick A. Lee and Jagadeesh S. Moodera, Proc. Natl. Acad. Sci. 117 (16) 8775-8782 (Apr. 21, 2020)