Magnetoelastic Transport-Path Reconstruction and Giant Magnetotransport Responses in a Two-Dimensional Antiferromagnet

Abstract: Nonvolatile magnetotransport responses in a single magnetic material have generally not been expected to exhibit a large ON/OFF ratio, because they are usually tied to spin-orbit coupling and therefore remain relatively weak. Here we show, contrary to this expectation, that giant nonvolatile magnetotransport can arise in a single magnetic material through magnetoelastic reconstruction of nonrelativistic real-space transport paths. Using the two-dimensional antiferromagnet FePS$_{3}$ as a representative system, first-principles quantum transport calculations reveal that charge transport is strongly tied to its quasi-one-dimensional zigzag sublattice chains and, under suitable doping, can even become confined to them. Moreover, strain lifts the degeneracy among symmetry-related zigzag variants and thus reorients these transport paths through magnetoelastic coupling. As a result, both the longitudinal and transverse conductivities change dramatically, yielding a giant magnetoelastic magnetoresistance of up to $10^{4}$% and an energy-independent Hall ratio that far exceeds the spontaneous Hall ratios found in conventional magnets. These results establish a route to exploiting symmetry-related magnetic variants and their associated transport paths for reconfigurable, high-performance spintronic devices with large nonvolatile readout contrast.

• The paper demonstrates a theoretical model where strain reorients charge transport in monolayer FePS₃, yielding a giant magnetoresistance of ~10⁴%.
• It employs first-principles quantum transport calculations to reveal anisotropic, spin-polarized conductance and a sign-reversible magnetoelastic Hall effect.
• The findings suggest new spintronic device designs that exploit sublattice geometry for high-performance memory and logic applications.

Magnetoelastic Transport-Path Reconstruction and Giant Magnetotransport in 2D Antiferromagnets

Introduction

This paper presents a comprehensive theoretical analysis of magnetoelastic transport-path reconstruction and its role in producing giant magnetotransport responses within a single two-dimensional antiferromagnet. The authors challenge established paradigms by demonstrating that high-contrast, nonvolatile magnetotransport phenomena, typically associated with multilayer heterostructures or spin-orbit-driven mechanisms, can occur intrinsically in a single magnetic material. The focus is on monolayer FePS₃ as the prototypical system, leveraging first-principles quantum transport calculations to elucidate confinement of charge transport to quasi-one-dimensional zigzag sublattice chains and the reorientation of transport paths by strain, yielding dramatic longitudinal and transverse conductivity modulations.

Physical Mechanism: Sublattice-Resolved Transport and Magnetoelastic Coupling

The central physical mechanism arises from the interplay between antiferromagnetic order and real-space sublattice geometry. In zigzag-ordered 2D antiferromagnets like FePS₃, charge carriers, especially under electron doping, propagate predominantly along the chain direction associated with ferromagnetically-aligned sublattices. The magnetoelastic coupling modifies exchange interactions among sublattices by applying shear strain, selectively stabilizing one of the three symmetry-equivalent zigzag magnetic variants oriented at 0°, +60°, and −60°.

This lifting of degeneracy between zigzag variants leads to reorientation of transport paths, fundamentally reconfiguring the directional conductivity tensor. The intra-sublattice conductance is highly spin-polarized and dominant along the chain direction, while inter-sublattice conductance is suppressed due to spin filtering, resulting in spatially anisotropic transport with direction-selective Néel spin currents.

Numerical Results: Giant Magnetoresistance and Hall Response

The paper’s quantum transport calculations yield quantified transport responses, notably:

• Longitudinal Magnetoresistance (MR): Upon switching between zigzag variants through strain, the MR in the y-direction reaches ~10⁴%, far exceeding conventional anisotropic MR and comparable to GMR or TMR values.
• Transverse Hall Ratio: The magnetoelastic Hall effect manifests as a sign-reversible transverse response in Z-2 and Z-3, tied directly to transport-path reorientation. Remarkably, the Hall ratio $|\sigma_{xy}/\sigma_{xx}|$ is energy-independent and determined purely by the zigzag path deflection (tan60° = √3), vastly surpassing spontaneous Hall ratios in traditional ferromagnets.
• Nonvolatility and Path Switching: The energy landscape calculated for each zigzag variant under strain shows pronounced stabilization and significant energy splitting, enabling nonvolatile path switching with feasible experimental strain magnitudes.

These results are robust under moderate disorder and persist in the p-doped regime, albeit with reduced MR due to weaker spin polarization, emphasizing the generality of the magnetoelastic transport-path reconstruction mechanism.

Implications for Spintronics

The findings reframe design principles for spintronic devices, shifting emphasis from SOC-driven moment switching to exploitation of sublattice orientation and geometry as tunable degrees of freedom. The ability to electrically distinguish stable, symmetry-related sublattice configurations with giant transport contrast in a single antiferromagnet opens pathways for:

• Structurally simplified spintronic memory and logic elements
• Reconfigurable device architectures employing strain, electric, or thermal fields for switching
• Enhanced readout contrast conducive to high-performance applications, surpassing limitations of single-layer ferromagnets

The mechanism is not unique to zigzag antiferromagnets but is extendable to other systems with low-dimensional magnetic sublattices whose orientations and couplings can be controlled in-plane.

Future Directions in AI-Driven Materials Design

These results suggest further theoretical and computational exploration of magnetoelastic effects in broader classes of antiferromagnets, including altermagnets and ferrimagnets, particularly those accessible to 2D exfoliation and carrier doping via electrostatic gating. Machine learning and AI-driven materials screening could accelerate identification of candidate compounds with tailored sublattice geometries and robust magnetoelastic coupling.

Interfacing the described mechanism with spin-torque approaches or multi-modal perturbations (electric, magnetic, thermal, optical) could enable deterministic switching of transport paths, expanding device functionalities.

Conclusion

This work establishes magnetoelastic sublattice-path reconstruction as a potent route toward realizing giant, nonvolatile magnetotransport responses in 2D antiferromagnets such as FePS₃. The theoretical predictions provide strong quantitative evidence, highlight fundamentally new design principles for spintronics, and underscore the critical role of symmetry, lattice geometry, and strain in enabling functional reconfigurability within single magnetic materials. The implications extend both practical device architectures and theoretical understanding, with open questions regarding broader material applicability and experimental realization.