Successive magnetic field-induced transitions and colossal magnetoelectric effect in Ni$_{3}$TeO$_{6}$

TL;DR

This paper reports a high-field phase transition in Ni$_{3}$TeO$_{6}$ that induces a colossal magnetoelectric effect, revealing complex spin structures and exchange interactions that enhance magnetoelectric coupling.

Contribution

It introduces the discovery of a 52 T metamagnetic transition with a large polarization change and provides a microscopic model explaining the underlying physics.

Findings

Colossal polarization change of 0.3 μC/cm² at 52 T

Complex spin structure driven by exchange interactions

Microscopic model describing high-field transition

Abstract

We report the discovery of a metamagnetic phase transition in a polar antiferromagnet Ni$_3$TeO$_6$ that occurs at 52 T. The new phase transition accompanies a colossal magnetoelectric effect, with a magnetic-field-induced polarization change of 0.3 $\mu$C/cm$^2$, a value that is 4 times larger than for the spin-flop transition at 9 T in the same material, and also comparable to the largest magnetically-induced polarization changes observed to date. Via density-functional calculations we construct a full microscopic model that describes the data. We model the spin structures in all fields and clarify the physics behind the 52 T transition. The high-field transition involves a competition between multiple different exchange interactions which drives the polarization change through the exchange-striction mechanism. The resultant spin structure is rather counter-intuitive and complex, thus providing new insights on design principles for materials with strong magnetoelectric coupling.