Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2610.23473

Magnetic Field-assisted Crystallographic Selection During Grain Growth in Non-Magnetic Polycrystals: A Phase-Field Study

Rakesh Maurya·Soumya Bandyopadhyay·Somnath Bhowmick·Rajdip Mukherjee
View original source ↗Read source document ↗Export metadata ↓

Abstract

Magnetic fields drive grain boundary migration in non-magnetic systems through anisotropic susceptibility, yet how the local orientation can affect the resulting collective grain growth behavior remains unclear. We employ a phase-field model to investigate magnetic-field-assisted grain growth in the diamagnetic Bi. This study provides a mechanistic basis for using static and dynamically varied magnetic fields to control texture development and grain growth kinetics in weakly magnetic materials. We also identify the conditions under which magnetic-field-driven orientation selection produces a distinct bimodal grain-size distribution. The bicrystal studies establish that boundary migration is governed by the magnetic free-energy difference between differently oriented grains, while polycrystalline field-sweep simulations reveal a transition from capillary-dominated coarsening to magnetically biased texture selection. For unbiased orientation distributions, magnetic selection remains distributed; however, when a small population of grains is strongly favored, the driving force localizes and exhibits bimodal coarsening characterized by enlarged favored grains embedded within a fine-grained matrix, even without grain boundary energy anisotropy, particle pinning, or heterogeneity. The field removal and field reorientation simulations further show that magnetic field history can redirect the coarsening pathway.

Explore related subjects

cond-mat.mtrl-sci

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Rakesh Maurya, Soumya Bandyopadhyay, Somnath Bhowmick, Rajdip Mukherjee. 2026-10-16. Magnetic Field-assisted Crystallographic Selection During Grain Growth in Non-Magnetic Polycrystals: A Phase-Field Study. https://arxiv.org/abs/2610.23473

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Towards decoding the structure of water-magnetite interface

The molecular structure of water at iron-oxide interfaces is determined by the protonation state, orientation and population of interfacial OH species. These microscopic features can be decoded by combining surface-specific vibrational spectroscopy with reactive and accurate molecular dynamics simulations. In this way, it could be possible to connect the measured nonlinear optical response to specific molecular configurations at the magnetite-water interface, resolving the interfacial water structure. We investigated magnetite films in contact with liquid water at neutral and alkaline pH using phase-resolved sum-frequency generation (SFG) spectroscopy in the OH/OD stretching region and Fresnel correction of the optical response. In parallel, neural-network-potential molecular dynamics simulations were used to model the water-magnetite interface and identify interfacial water species, quantify their orientations, hydrogen-bonding environments and lifetimes, and compute species resolved SFG spectra. The combined analysis assigns distinct spectral features to dissociated surface OH groups, hydroxyls and water molecules adsorbed on octahedral iron sites, water bound at dissociation sites and water molecules above tetrahedral rows. The simulations reveal a reactive interfacial hydroxyl network with nanosecond-scale rearrangements and strong species-dependent hydrogen bonding. Experimentally, the SFG spectra show pronounced pH dependence, consistent with changes in surface charge and hydroxylation. A systematic difference between measured and computed SFG spectra indicates that the assumed surface model of magnetite does not fully represent the aqueous interface. This discrepancy provides a molecular constraint for improved models of magnetite-water interfaces and highlights SFG spectroscopy/ML-MD comparison as a valuable route to resolving oxide-water interfacial structures.

cond-mat.mtrl-sci↗
arXiv2026

Electron--phonon matrix elements from eigenvalue projection within the projector augmented-wave method

We present a finite-displacement approach to electron--phonon matrix elements that requires only eigenvalues and wave functions from the displaced calculations, for both norm-conserving pseudopotentials and the projector augmented-wave (PAW) method. Extending the eigenvalue-projectability approach, previously formulated for norm-conserving pseudopotentials, we reconstruct the displaced Hamiltonian from the displaced eigenvalues and from overlaps evaluated in the PAW metric of each displaced structure. Analytic terms constructed from the PAW dataset then yield the all-electron matrix element, without derivatives of the local potential or of the PAW strengths. The approach therefore applies in principle to any electronic-structure method available in PAW. To reduce the supercell cost, we combine it with nondiagonal supercells that sample the Brillouin zone equivalently to the primitive cell and recover the full matrix elements by crystal symmetry. Implemented in the ARES-EPC code, the method reproduces matrix elements from density-functional perturbation theory and from VASP+phelel for seven materials with mean absolute errors below 0.5 meV. Nondiagonal supercells reproduce the diagonal-supercell results to the same accuracy and reduce the cost of the displaced calculations by up to a factor of 23.

cond-mat.mtrl-sci↗
arXiv2026

Light-Induced Even-Parity Unidirectionally Polarized Spin Splitting in Coplanar Antiferromagnets

When a coplanar antiferromagnet (AFM) with $xy$-plane magnetic moments exhibits a spin-split band structure and unidirectional spin polarization along $z$, the spin polarization is forced to be an odd function of momentum by the fundamental symmetry $[\bar{C}_{2z}\|\mathcal{T}]$. Coplanar AFMs displaying such odd-parity, unidirectionally polarized spin splittings are known as odd-parity magnets. In this work, we propose the realization of their missing even-parity counterparts. We begin by deriving the symmetry conditions required for an even-parity, out-of-plane spin splitting. We then show that irradiating a spin-degenerate coplanar AFM with circularly polarized light lifts the $[\bar{C}_{2z}\|\mathcal{T}]$ constraint, dynamically generating this even-parity state. Specifically, the light-induced unidirectionally polarized spin splitting exhibits a $d$-wave texture in momentum space, akin to that of a $d$-wave altermagnet. We prove this texture's robustness against spin canting and propose time-, spin- and angle-resolved photoemission photocurrent as a direct probe. Our work demonstrates that optical driving can generate novel spin-split phases in coplanar AFMs, thereby diversifying the landscape of materials exhibiting distinct spin splittings.

cond-mat.mtrl-sci↗