arXiv subjects

Linding Yuan

Publications and source records attributed to Linding Yuan.

4 recordsLinked to original sources

arXiv2026

Dynamical Nonrelativistic Spin Splitting via THz Nonlinear Phononics

Nonrelativistic spin splitting (NRSS) in collinear antiferromagnets offers a route to high-frequency spintronics immune to stray fields, but its dynamic control has remained elusive. We demonstrate, using density functional theory (DFT) and nonlinear phononics, that THz laser pulses can achieve ultrafast, reversible control of NRSS on picosecond timescales in antiferromagnets. We derive two symmetry criteria, accounting for phonon and magnetic wavevector compatibility and order-parameter parity, to identify which Raman-active phonon modes can activate or amplify NRSS. Applying these rules to NiO and LaFeO$_3$, we show that resonant driving of an infrared-active mode at 11.08 THz transiently converts spin-degenerate NiO into an NRSS state via biquadratic anharmonic coupling, generating a time-averaged spin splitting of $\sim$40 meV. In LaFeO$_3$, selective excitation amplifies the existing NRSS by about 100%. In both cases, the induced spin splitting is accompanied by a transient SOC-induced net moment detectable via the magneto-optical Kerr effect. This framework establishes nonlinear phononics as a general route for ultrafast manipulation of spin-split antiferromagnetic phases well beyond the reach of static strain.

cond-mat.mtrl-sci↗

arXiv2025

Anion correlation induced nonrelativistic spin splitting in rutile antiferromagnets

Many studies of non-relativistic spin-splitting (NRSS), or altermagnetism, have focused on idealized, perfectly ordered crystals, relying on symmetry-based approaches to identify candidate materials. Here, we theoretically investigate how local short-range ordering (SRO) influences NRSS of energy bands in partially ordered collinear antiferromagnetic iron oxyfluoride (FeOF). Using the cluster expansion method, we identify four nearly degenerate structures (energy difference $\leq 8$ meV per formula unit) that represent distinct snapshots of local plane-to-plane O/F correlations. Our density functional theory (DFT) results show robust NRSS along the $\Gamma$-M direction in all four structures, despite the absence of long-range order. The magnitude and character of the splitting depend sensitively on the specific direction of anion correlations, effects that are not fully captured in high-symmetry average structures. Notably, two configurations ($Pmc2_1$ and $Pm$) exhibit $\Gamma$-point spin splitting absent in ordered FeF$_2$ and a virtual crystal approximation model of FeOF. We further predict distinct magneto-optical Kerr effect (MOKE) signatures, enabling experimental detection of SRO-driven electronic structure changes. These results highlight heteroanionic compounds as a promising design space for NRSS antiferromagnets, with experimentally synthesized FeOF already exhibiting a substantially higher N\'eel temperature (315\,K) than FeF$_2$ (79\,K).

cond-mat.mtrl-sci↗

arXiv2021

The different shapes of spin textures as a journey through Brillouin zone chiral and polar symmetries

Crystallographic space group symmetry (CPGS) such as polar and nonpolar crystal classes have long been known to classify compounds that have spin-orbit-induced spin splitting. While taking a journey through the Brillouin Zone (BZ) from one k-point to another for a fixed CPGS, it is expected that the wavevector point group symmetry (WPGS) can change, and consequently a qualitative change in the texture of the spin polarization (the expectation value of spin operator $\vec{S}^{nk_{0}}$ in Bloch state $u(n,k)$ and the wavevector $k_0$). However, the nature of the spin texture (ST) change is generally unsuspected. In this work, we determine a full classification of the linear-in-$k$ spin texture patterns based on the polarity and chirality reflected in the WPGS at $k_0$. The spin-polarization vector $\vec{S}^{nk_{0}}$ controlling the ST is bound to be parallel to the rotation axis and perpendicular to the mirror planes and hence, symmetry operation types in WPGSs impose symmetry restriction to the ST. For instance, the ST is always parallel to the wavevector $k$ in non-polar chiral WPGSs since they contain only rotational symmetries. Some consequences of the ST classification based on the symmetry operations in the WPGS include the observation of ST patterns that are unexpected according to the symmetry of the crystal. For example, it is usually established that spin-momentum locking effect requires the crystal inversion symmetry breaking by an asymmetric electric potential. However, we find that polar WPGS can have this effect even in compounds without electric dipoles or external electric fields. We use the determined relation between WPGS and ST as a design principle to select compounds with multiple ST near band edges at different $k$-valleys. Based on high-throughput calculations for 1481 compounds, we find 37 previously fabricated materials with different ST near band edges.

cond-mat.mtrl-sci↗

arXiv2018

Uncovering and tailoring hidden Rashba spin-orbit splitting in centrosymmetric crystals

Hidden Rashba and Dresselhaus spin-splittings in centrosymmetric crystals with subunits (sectors) having non-centrosymmetric symmetries (the R-2 and D-2 effects) have been predicted and observed experimentally, but the microscopic mechanism remains unclear. Here we demonstrate that the spin-splitting in R-2 is enforced by specific symmetries (such as the non-symmorphic in the present example) which ensures that the pertinent spin wavefunctions segregate spatially on just one of the two inversion-partner sectors and thus avoid compensation. This finding establishes a common fundamental source for the conventional Rashba (R-1) effect and the R-2 effect, both originating from the local sector symmetries, rather than from the global crystal asymmetry alone for R-1 per se. We further show that the effective Hamiltonian for the R-1 effect is also applicable for the R-2 effect, but applying a symmetry-breaking electric field to an R-2 compound produces different spin-splitting pattern than applying a field to a trivial (non-R-2) centrosymmetric compound.

cond-mat.mtrl-sci↗