arXiv subjects

Xiaofan Shen

Publications and source records attributed to Xiaofan Shen.

4 recordsLinked to original sources

arXiv2026

A General Theory of Chiral Splitting of Magnons in Two-Dimensional Magnets

Magnons in antiferromagnets exhibit two chiral modes, providing an intrinsic degree of freedom for magnon-based computing architectures and spintronic devices. Electrical control of chiral splitting is crucial for applications, but remains challenging. Here, we propose the concept of extrinsic chiral splitting, involving alternating and ferrimagnet-like types, which can be induced and controlled by an electric field. A symmetry framework based on 464 collinear spin layer groups is established to classify chiral splitting characteristics and electric field responses in two-dimensional magnets. We further elucidate how the spin layer group determines the type of alternating chiral splitting and the dominant lowest-order magnetic exchange interaction. We demonstrate electric-field control over the magnitude and sign of the chiral splitting, enabling control of the spin Seebeck and Nernst effects related to thermal spin transport. This work provides a general theory for electric field manipulation of magnon chirality, paving the way for low-power magnonic logic devices.

cond-mat.mtrl-sci↗

arXiv2025

Manipulation of topology by electric field in breathing kagome lattice

Magnetic kagome lattices have attracted much attention recently due to the interplay of band topology with magnetism and electronic correlations, which give rise to a variety of exotic quantum states. A common structural distortion of the kagome lattice is the breathing mode, which can significantly influence the magnetism and band characteristics. However, the modulation of breathing mode and the associated topological phenomena remain rarely explored. Here, we demonstrate that the coupling of breathing modes with ferroelectricity, magnetism, and band topology in the M3X8 monolayer system enables electric field manipulation of topological spin structure and electronic states. The breathing mode mainly occurs in materials containing early 4d/5d transition metal elements and can be reversed or even suppressed via ferroelectric switching in low-barrier materials. Importantly, electric field-induced switching of the breathing mode can alter the chirality of the topological spin structure, or trigger a transition from a topological trivial insulator to a Chern insulator. This work paves the way for exploring novel physical phenomena driven by breathing modes in kagome materials.

cond-mat.mtrl-sci↗

arXiv2024

Negative piezoelectricity in quasi-two/one-dimensional ferroelectrics

In recent years, the investigation of low-dimensional ferroelectrics has attracted great attention for their promising applications in nano devices. Piezoelectricity is one of the most core properties of ferroelectric materials, which plays the essential role in micro-electromechanical systems. Very recently, the anomalous negative piezoelectricity has been predicted/discovered in many quasi-two-dimensional layered ferroelectric materials. In this Topical Review, we will briefly introduce on the negative piezoelectricity in quasi-two/one-dimensional ferroelectrics, including its fundamental concept, typical materials, theoretical predictions, as well as experimental phenomena. The underlying physical mechanisms for negative piezoelectricity are divergent and varying from case by case, which can be categorized into four types. First, the soft van der Waals layer is responsible for the volume shrinking upon pressure while the electric dipoles is from non van der Waals layer. Second, the noncollinearity of local dipoles creates a ferrielectricity, which leads to orthogonal ferroelectric and antiferroelectric axes. Third, the electric dipoles come from interlayer/interchain couplings, which can be enhanced during the volume shrinking. Fourth, the special buckling structure contributes to local dipoles, which can be enhanced upon pressure. In real materials, more than one mechanism may work together. Finally, the future directions of negative piezoelectricity and their potential applications are outlooked.

cond-mat.mtrl-sci↗

arXiv2023

Jahn-Teller distortion driven ferromagnetism in a perovskite fluoride monolayer

The Jahn-Teller distortion and the resulting orbital order usually cause some fascinating correlated electronic behaviors, and generally lead to antiferromagnetism in perovskite bulks. Here we demonstrate that the Jahn-Teller distortion present in the perovskite fluoride KCrF$_3$ bulk can be retained to the two-dimensional limit, resulting in a staggered orbital order and ferromagnetism in the perovskite monolayer. Octahedral tilt and rotation distortion also appear in the ground-state structure of the perovskite monolayer, which have minor effects on the electronic and magnetic properties with respect to the Jahn-Teller distortion. In addition, in the prototype phase without structural distortion, the partial occupation of the $e_g$ orbitals leads to a ferromagnetic metallic state. This work facilitates the design of two-dimensional ferromagnets and functional properties based on Jahn-Teller distortion and orbital order

cond-mat.mtrl-sci↗