arXiv subjects

Saurav Shenoy

Publications and source records attributed to Saurav Shenoy.

4 recordsLinked to original sources

arXiv2026

A Structure-Preserving Scheme for the Time-Dependent Ginzburg-Landau Model with BCS Gap Coupling

We propose a structure-preserving scheme for a hybrid model that couples the time-dependent Ginzburg-Landau (TDGL) equation of superconducting vortex dynamics and the nonlinear Bardeen-Cooper-Schrieffer (BCS) gap equation. This formulation is consistent with the classical TDGL equation in the near-critical temperature, while extending the applicability of the existing TDGL model to regimes beyond the critical temperature. The resulting system poses significant computational challenges due to its nonlinear and coupled structure. To achieve stable and reliable simulations of the vortex dynamics and accompanying morphological transitions, we develop a maximum bound preserving, energy-stable implicit-explicit (IMEX) scheme. The structure-preserving properties of the scheme are rigorously established, ensuring long-time stability and physical consistency. Through two- and three-dimensional simulations, the hybrid model successfully captures the temporal and spatial formation and alignment of vortices and the suppression of superconductivity under increasing magnetic fields, demonstrating both the accuracy and robustness of the proposed computational approach.

math.NA↗

arXiv2025

Symmetry-designed BiFeO3 single domain spin cycloid for efficient spintronics

Deterministic control of coupled ferroelectric and antiferromagnetic orders remains a central challenge in multiferroics, limiting their integration into functional magnetoelectrics and magnonic-devices. (111)pc BiFeO3 with a robust single spin cycloid, offers direct magnetoelectric-coupling and a platform for efficient spin transport, yet multi-magnetic domains and ferroelectric-fatigue have prevented reproducible control. Here, we show that anisotropic-compressive in-plane strain stabilizes a single antiferromagnetic domain with unique spin-cycloid vector, by breaking the symmetry of the (111)pc plane. Epitaxial BiFeO3 films grown on orthorhombic NdGaO3 (011)o [(111)pc] substrates impose the required anisotropic in-plane strain and stabilizes single antiferromagnetic domain, as confirmed through direct imaging with scanning NV microscopy and non-resonant-x-ray-magnetic-scattering. Remarkably, these engineered films exhibit deterministic and non-volatile 180° switching of ferroelectric and single antiferromagnetic domains over 1,000 cycles. The monodomain state also enables anisotropic and threefold enhanced magnon transport with reduced scattering. Thus, symmetry-designed (111)pc monodomain BiFeO3 offers a robust platform for advanced magnetoelectric and magnonic applications.

cond-mat.mtrl-sci↗

arXiv2024

MICROSIM: A high performance phase-field solver based on CPU and GPU implementations

The phase-field method has become a useful tool for the simulation of classical metallurgical phase transformations as well as other phenomena related to materials science. The thermodynamic consistency that forms the basis of these formulations lends to its strong predictive capabilities and utility. However, a strong impediment to the usage of the method for typical applied problems of industrial and academic relevance is the significant overhead with regard to the code development and know-how required for quantitative model formulations. In this paper, we report the development of an open-source phase-field software stack that contains generic formulations for the simulation of multi-phase and multi-component phase transformations. The solvers incorporate thermodynamic coupling that allows the realization of simulations with real alloys in scenarios directly relevant to the materials industry. Further, the solvers utilize parallelization strategies using either multiple CPUs or GPUs to provide cross-platform portability and usability on available supercomputing machines. Finally, the solver stack also contains a graphical user interface to gradually introduce the usage of the software. The user interface also provides a collection of post-processing tools that allow the estimation of useful metrics related to microstructural evolution.

cond-mat.mtrl-sci↗

arXiv2024

Splitting Instability in Superalloys: A Phase-Field Study

Precipitation-strengthened alloys, such as Ni-base, Co-base and Fe-base superalloys, show the development of dendrite-like precipitates in the solid state during aging at near-$γ^{\prime}$ solvus temperatures. These features arise out of a diffusive instability wherein, due to the point effect of diffusion, morphological perturbations over a growing sphere/cylinder are unstable. These dendrite-like perturbations exhibit anisotropic growth resulting from anisotropy in interfacial/elastic energies. Further, microstructures in these alloys also exhibit "split" morphologies wherein dendritic precipitates fragment beyond a critical size, giving rise to a regular octet or quartet pattern of near-equal-sized precipitates separated by thin matrix channels. The mechanism of formation of such morphologies has remained a subject of intense investigation, and multiple theories have been proposed to explain their occurrence. Here, we developed a phase-field model incorporating anisotropy in elastic and interfacial energies to investigate the evolution of these split microstructures during growth and coarsening of dendritic $γ^{\prime}$ precipitates. Our principal finding is that the reduction in elastic energy density drives the development of split morphology, albeit a concomitant increase in the surface energy density. We also find that factors such as supersaturation, elastic misfit, degree of elastic anisotropy and interfacial energy strongly modulate the formation of these microstructures. We analyze our simulation results in the light of classical theories of elastic stress effects on coarsening and prove that negative elastic interaction energy leads to the stability of split precipitates.

cond-mat.mtrl-sci↗