Gate-tunable anisotropic Josephson diode effect in topological Dirac semimetal Cd$_3$As$_2$ nanowires

TL;DR

This study demonstrates a gate-tunable, anisotropic Josephson diode effect in topological Dirac semimetal Cd$_3$As$_2$ nanowires, revealing complex interplay between bulk and surface states and serving as a probe for hidden topological superconductivity.

Contribution

It provides the first systematic analysis of the anisotropic and gate-tunable Josephson diode effect in Cd$_3$As$_2$ nanowire junctions, including a phenomenological model and temperature-dependent insights.

Findings

Diode effect is highly anisotropic and tunable by gate voltage.

Temperature dependence reveals coexistence of multiple transport channels.

Angular dependence of the diode effect is captured by a comprehensive model.

Abstract

The intrinsic Josephson diode effect (JDE) has recently attracted considerable attention due to its sensitivity to broken symmetries in Josephson junctions, offering a powerful probe for uncovering hidden symmetry-breaking mechanisms in materials. The presence of higher-harmonic components in the current-phase relation, together with spin-orbital coupling, makes topological materials ideal platforms to explore this effect. In this work, we present a systematic study of the JDE in type-I topological Dirac semimetal Cd$_3$As$_2$ nanowire-based Josephson junctions. We observe a pronounced gate-tunable and highly anisotropic diode response under different magnetic-field orientations. By developing a comprehensive phenomenological model, we capture the angular dependence of the diode effect and, through temperature-dependent measurements, disentangle the respective contributions from bulk and topological surface states. Notably, anomalies in the temperature dependence of the diode efficiency reveal the coexistence of multiple transport channels, highlighting the Josephson diode effect as a sensitive probe of hidden topological superconducting states.