Detection of Fermi arcs in Weyl semimetals through surface negative refraction

Abstract

One of the main features of Weyl semimetals is the existence of Fermi arc surface states at their surface, which cannot be realized in pure two-dimensional systems in the absence of many-body interactions. Due to the gapless bulk of the semimetal, it is, however, challenging to observe clear signatures from the Fermi arc surface states. Here, we propose to detect such novel surface states via perfect negative refraction that occurs between two adjacent open surfaces with properly orientated Fermi arcs. Specifically, this phenomenon visibly manifests in nonlocal transport measurement, where the negative refraction generates a return peak in the realspace conductance. This provides a unique signature of the Fermi arc surface states. We discuss the appearance of this peak in both inversion-and time-reversal-symmetric Weyl semimetals, where the latter exhibits conductance oscillations due to multiple negative refraction scattering events.

Conductance oscillation in surface junctions of Weyl semimetals

“…We adopt the following effective two-band k • p model, which describes a T -symmetric Weyl semimetal with four Weyl points [51,52]:…”

“…3(a). To simulate the FAs in real materials [49,[61][62][63], we have introduced an on-site potential V on the top layer of the WSM lattice to introduce surface dispersion that yields curved FAs [51,52].…”

“…Recent progress has also shown that the configurations of the FAs are sensitive to the details of the sample boundary [47][48][49], thus opening the possibility for engineering FAs and exploring their novel effects and potential applications through surface device fabrication and transport measurements. In contrast to the photoemission spectroscopy experiments, the surface transport measurement has the advantage of extracting useful information of the spatial distribution of the surface states [50][51][52].…”

Phonon-limited Transport and Fermi Arc Lifetime in Weyl Semimetals

“…The gapless bulk Weyl nodes must coexist on general grounds with gapless and topologically protected Fermiarc surface states, which connect the projections on the surface Brillouin zone of different Weyl nodes. These surface states are chiral, i.e., have a unidirectional sense of propagation, and define open curves as Fermi surface segments [21][22][23][24][25][26][27][28][29][30][31][32][33][34]. The Fermi arc parts of the Fermi surface seamlessly merge with the bulk quasiparticle parts at the arc termination points [6,23,35,36].…”

Andreev Reflection in Fermi Arc Surface States of Weyl Semimetals

“…With this prospect, it is of great importance to extract and analyze clear signatures of the FA from measurement information in the presence of gapless bulk states. Surface transport measurements provide a natural solution to this goal because the setups contact directly to the sample boundaries [43,44].…”