Zero-field current-induced Hall effect in ferrotoroidic metal

TL;DR

This study demonstrates a zero-field nonlinear Hall effect in ferrotoroidic metal UNi4B, driven by current-induced magnetization below the transition temperature, revealing unique magnetoelectric properties of ferrotoroidic materials.

Contribution

It provides the first experimental evidence of a zero-field Hall effect linked to current-induced magnetization in a ferrotoroidic metal, highlighting a novel magnetoelectric phenomenon.

Findings

Zero-field Hall voltage appears below TN.

Hall voltage scales with current density squared.

Current-induced magnetization matches previous measurements.

Abstract

We have performed precise Hall measurements for the ferrotoroidic candidate material UNi4B. Below Neel temperature TN ~ 20 K (corresponding to the ferrotoroidic transition temperature), a Hall voltage becomes finite even at zero field and changes proportional to the square of current density; by contrast, it is almost zero above TN. Moreover, we have found that a current-induced magnetization estimated from our Hall effect measurements is qualitatively consistent with the previous directly measured value. These results provide strong evidence for a magnetoelectric phenomenon uniquely in ferrotoroidic metals -- a zero-field nonlinear Hall effect resulting from the current-induced magnetization connecting the ferrotoroidal moments.