Nonreciprocal Transport in chiral Mo3Al2C Near the Superconducting to Normal Transition

TL;DR

This study reveals tunable nonreciprocal electrical transport in chiral Mo3Al2C near its superconducting transition, driven by the interplay of lattice chirality, charge-density-wave, and magnetic effects.

Contribution

It demonstrates that bulk Mo3Al2C exhibits significant nonreciprocal transport linked to its chiral and polar properties, especially near the superconducting transition, providing a new platform for nonreciprocal devices.

Findings

Enhanced nonreciprocal second-harmonic signal near phase boundary

Persistent nonreciprocal response under perpendicular magnetic fields

Nonreciprocal transport rooted in chirality, polarity, and superconductivity

Abstract

We investigate nonreciprocal electrical transport in bulk single-crystalline Mo3Al2C, a material known to host crystallographic chirality, a polar charge-density-wave instability, and a superconducting transition near 8 K. Using AC transport measurements to analyze the first-harmonic and second-harmonic resistance responses, we observe a distinct nonreciprocal second-harmonic signal that is significantly enhanced near the boundary of the normal and superconducting phases. Phenomenologically, this response arises from direction-dependent coupling between the external magnetic field and the current-induced intrinsic magnetization within the chiral lattice. Furthermore, a persistent nonreciprocal response observed under perpendicular magnetic fields suggests a toroidal-induced effect linked to the electric polarization emerging from the charge-density-wave phase. These results demonstrate that bulk Mo3Al2C serves as an intrinsic platform for tunable nonreciprocal transport rooted in the interplay of chirality, polarity, and superconductivity.