Quantum Interference in SnTe nanowires*

SnTe is a topological crystalline insulator (TCI) [1] and is predicted to undergo a phase transition to a higher-order topological state [2] by breaking crystal symmetry. These higher-order topological insulators (HOTI) have not been experimentally realized; they host hinge states on the boundary of two gapped surfaces, leading to conducting hinges. When combined with a superconductor, this system could host parafermions on a pair of hinge states due to the one-dimensional character of these states. Detecting the 2D surface and 1D hinge states in this material is therefore a key objective.

To this end, we perform transport measurements on SnTe nanowires. However, probing the topological surface states of SnTe is challenging due to a high bulk carrier density (~10²¹ cm^-3) and electrostatic gating therefore has a negligible effect. Nevertheless, conductance oscillations are observed as function of source-drain and backgate voltage which we attribute to Fabry-Pérot oscillations, a coherent transport behaviour indicating a (quasi-) ballistic transport channel [3]. The period of the oscillation corresponds to a characteristic length closely resembling the physical length of the device. Furthermore, the conductance variation on top of the background signal has a magnitude corresponding to one ballistic transport channel, hinting towards transport through a SnTe surface state.

 

[1] Nature Phys 8, 800–803 (2012).

[2] Nat Rev Phys 3, 283–297 (2021).

[3] Nano Letters 10 (9), 3439-3445 (2010).