Anomalous Magnetoelectric Coupling in the Paramagnetic State of a Chiral and Polar Magnet

Abstract

AbstractChiral magnets are excellent platforms for studying intertwined spin, charge, orbit, and lattice degrees of freedom in solid‐state materials. In this work, the anomalous magnetoelectric behavior in a chiral magnet K2Co2(SO4)3 is demonstrated using comprehensive experimental probes. This material adopts a P213 chiral cubic structure at room temperature. Based on the results of high‐resolution synchrotron X‐ray diffraction, this study shows that the low‐temperature (<130 K) crystal structure is a P21 monoclinic phase, both polar and chiral. Magnetic and thermodynamic measurements reveal highly frustrated magnetic interactions and possible non‐collinear antiferromagnetic ordering at an extremely low temperature ≈0.6 K. Critically, anomalous magnetoelectric correlations are experimentally detected in its paramagnetic temperature regime, which can arise from the synergetic interplay between magnetoelastic and piezoelectric effects. These findings thus indicate that K2Co2(SO4)3 is a unique material, displaying multiple emergent structural and magnetic phenomena. This is attributed to both its overall crystallographic symmetry and the fact that its magnetic ions are located at low‐symmetry sites.