arXiv subjects

Yuchuan Yao

Publications and source records attributed to Yuchuan Yao.

3 recordsLinked to original sources

arXiv2026

Temperature-invariant magneto-optical Kerr effect in a noncollinear antiferromagnet

Noncollinear antiferromagnets exhibit anomalous Hall and magneto-optical Kerr effects driven by Berry curvature despite negligible net magnetization, promising ultrafast spintronic applications. While both effects are theoretically expected to reveal the intrinsic Berry curvature that serves as a spintronic memory bit, their quantitative interpretation is complicated by additional temperature-dependent contributions superimposed on the magnetic order parameter: extrinsic skew scattering in dc Hall transport, and optical-resonance effects in visible-wavelength Kerr measurements. Here we perform polar Kerr measurements at the infrared telecommunication wavelength (1550 nm) on epitaxial, stoichiometric Mn3NiN single crystal films, revealing for the first time a spontaneous Kerr signal that remains stable within a few percent over a 200 K range below the Néel temperature. This temperature-invariant intrinsic Kerr response contrasts with the strongly temperature-dependent anomalous Hall effect in the same sample dominated by extrinsic skew scattering. Our findings establish infrared Kerr effect as a robust, local probe of Berry curvature in noncollinear antiferromagnets, enabling quantitative characterization and advancing antiferromagnetic spintronic technologies.

cond-mat.str-el↗

arXiv2026

Direct imaging of a Berry curvature nematic state in a spin-compensated magnet

Density waves conventionally describe the periodic modulation of charge or spin, yet the spatial modulation of electronic geometry has remained elusive. Here, we report subtle micrometer-scale spatial modulations of the magneto-optical Kerr signal in the noncollinear antiferromagnet Mn3NiN with compensated spins, consistent with a magnetic-field-induced Berry curvature density wave . These Berry curvature modulations exhibit orientations unpinned from the crystal lattice, forming a nematic state that spontaneously breaks rotational symmetry. We attribute this spatial instability to field-induced spatial variations of the spin texture driven by competing magnetic interactions. This discovery unveils a new class of collective order in spin-compensated magnets mediated by the geometric phase of the wavefunction itself. Its wavelength is controlled by chemical doping and its amplitude by magnetic field, providing concrete tuning knobs for antiferromagnetic and altermagnetic spintronics.

cond-mat.str-el↗

arXiv2025

Direct imaging and control of Berry curvature in noncollinear antiferromagnetic single-crystal thin films

The discovery of the intrinsic anomalous Hall effect (AHE) in noncollinear antiferromagnets where transverse Hall voltage emerges without magnetic field, has opened a plethora of promising opportunities in antiferromagnetic devices. The key challenges limiting their full potential are (1) high-quality epitaxial thin-film growth and (2) the understanding of Berry curvature domain physics. Here, we focus on a noncollinear antiperovskite antiferromagnet Mn3NiN as a model system, successfully grown as a single-crystal epitaxial thin film. Combining multiple experiments supported by theoretical calculations, we probe the Berry curvature associated with antiferromagnetic Γ4g domains in Mn3NiN and its strong connection to an AHE. We directly image the intrinsic Berry curvature with high-resolution Sagnac microscopy, controlling spatial distribution and dynamics by varying temperature and applied magnetic fields. We discover that the Γ4g domains are switchable near the Néel transition, but become frozen and unresponsive to external stimuli at low temperature. This behavior enables the tuning of Berry-curvature driven AHE and magneto-optic Kerr effect responses through controlled experimental conditions. Our findings provide critical advancement of the fundamental understanding and wide tunability of Berry curvature in noncollinear antiferromagnets important for realization in potential spintronic applications.

cond-mat.mtrl-sci↗