Anomalous Magnetoelectric Entanglement in a Chiral Magnet

Chiral magnets are excellent platforms for studying intertwined spin, charge, orbit, and lattice degrees of freedom in solid-state materials. In this talk, I will demonstrate the anomalous magnetoelectric behavior in a chiral magnet K₂Co₂(SO₄)₃ using comprehensive experimental probes. This material adopts a P2₁3 chiral cubic structure at room temperature. Based on the high-resolution synchrotron x-ray diffraction results, we unambiguously prove that the low-temperature (<130 K) crystal structure is a P2₁ monoclinic phase, both polar and chiral, with the chiral dichroism and low-temperature domain configuration unveiled in microscopy study. Magnetic and thermodynamic measurements reveal highly frustrated magnetic interactions and possible non-collinear antiferromagnetic ordering at a fairly low temperature of around 0.6 K. Remarkably, an anomalous magnetoelectric response is experimentally detected in its paramagnetic temperature regime, which could arise from the synergetic interplay between magnetoelastic and piezoelectric effects. Our findings thus indicate that K₂Co₂(SO₄)₃ is a unique material, displaying multiple facets of emergent phenomena. We attribute this to both its overall crystallographic symmetry and the fact that its magnetic ions are located at low-symmetry sites.