Quantum interference in superposed lattices

TL;DR

This paper investigates quantum interference effects in charge transport of Cr with superposed lattices, revealing phase shifts in SdH oscillations caused by incommensurate orbits and orbit reconnection.

Contribution

It uncovers the origin of low-frequency SdH oscillations as quantum interference from incommensurate orbits in superposed lattices, explaining phase shifts in a novel material context.

Findings

Opposite phase of low-frequency SdH oscillations in different directions.

Quantum interference from incommensurate orbits causes observed phase shifts.

Reconnection of anisotropic orbits explains the pi-phase shift.

Abstract

Charge transport in solids at low temperature reveals a material's mesoscopic properties and structure. Under a magnetic field, Shubnikov-de Haas (SdH) oscillations inform complex quantum transport phenomena that are not limited by the ground state characteristics. Here, in elemental metal Cr with two incommensurately superposed lattices of ions and a spin-density-wave ground state, we reveal that the phases of several low-frequency SdH oscillations in sigma_xx (rho_xx) and sigma_yy (rho_yy) are opposite, contrast with oscillations from normal cyclotron orbits that maintain identical phases. We trace the origin of the low frequency SdH oscillations to quantum interference effects arising from the incommensurate orbits of Cr's superposed reciprocal lattices, and explain the observed pi-phase shift by the reconnection of anisotropic joint open and closed orbits.