Tuning nonlinear magnetoelectric responses in quantum materials

Speaker: A/Prof Julie Karel
Affiliation: Monash University

Abstract

Non-linear electronic responses underpin technologies such as rectification and wave mixing while serving as a sensitive probe of topology and symmetry in condensed matter. In this talk, I will discuss recent work demonstrating how higher-order electronic responses can be tuned via magnetic fields, nanostructuring, and disorder. First, I will report unexpected room-temperature higher order nonlinear electronic transport in the centrosymmetric quantum magnet, TbMn6Sn6. Occurring in both the longitudinal and transverse directions, this response exhibits complex temperature dependence tied to a spin-reorientation transition. We show that the field-dependent quantum metric component can be tuned via magnetic configuration, and that the higher-harmonic response sign can be controlled through chiral nanostructure patterning. Next, I will turn to the kagome metal YbCo6Ge6. Here, intrinsic structural disorder and short-range correlated motifs, rather than diminishing performance, act as the primary driver for a robust, anisotropic second order nonlinear transverse response (nonlinear Hall effect). Sustained from 2 K to 350 K, this effect achieves a nonlinear responsivity surpassing that of known disordered systems and engineered quantum heterostructures.