arXiv subjects

Masoumeh Davoudiniya

Publications and source records attributed to Masoumeh Davoudiniya.

4 recordsLinked to original sources

arXiv2026

Strain-stabilized altermagnetism and conductivity anisotropy in FeSb2

We show that FeSb2 experiences a transition from a conventional antiferromagnet to an altermagnet when tensile strain is applied. In the altermagnetic phase, the lifted Kramers degeneracy results in spin splitting up to ~0.2eV near the Fermi level even without spin-orbit coupling. The transition to the altermagnetic phase is accompanied by a dramatic change in the Fermi-surface geometry, which leads to a uniaxial conductivity anisotropy up to ~60%, much greater than those observed in typical ferromagnetic metals. Using density-functional theory and Wannier interpolated Fermi surfaces, we show that this magnetotransport behavior may function as an experimental indicator of the transition to the altermagnetic phase. These findings highlight FeSb2 as a versatile, strain-tunable platform for exploring and utilizing altermagnetic transport phenomena for spintronic devices.

cond-mat.mtrl-sci↗

arXiv2025

Lattice tuning of charge and spin transport in $β_{12}$-borophene nanoribbons

$β_{12}$-borophene nanoribbons (BNRs) exhibit magnetic zigzag edges, while other edge configurations are nonmagnetic. However, when the source, central, and drain regions of a logic device are all composed of zigzag BNRs (ZBNRs), the resulting spin polarization remains weak, unless a high voltage is applied. In this work, we demonstrate that lattice vibrations-introduced for example, via a thermal bath coupled to the central BNR-can enhance spin polarization in ZBNRs. This enhancement manifests as marked changes in the current-voltage characteristics, enabling direct experimental probing. In contrast, nonmagnetic edge configurations exhibit phonon-enhanced charge transport. We employ a tight-binding approach augmented with local electron-phonon interactions described by the Holstein model, and compute the phonon-renormalized Green's functions and transport currents using the Landauer-Büttiker formalism. The mechanism is supported by analyzing both spinless and spinful electronic dispersions and the corresponding density of states. Compared to the phonon-free edges, structural distortions lead to anisotropic electron-phonon couplings, which significantly modify both charge and spin transport. These results position phonon as an effective tuning parameter for optimizing borophene-based logic devices via engineered edge configurations.

cond-mat.mes-hall↗

arXiv2025

Efficient spin filtering through Fe$_4$GeTe$_2$-based van der Waals heterostructures

Utilizing ab initio simulations, we study the spin-dependent electronic transport characteristics within Fe$_4$GeTe$_2$-based van der Waals heterostructures. The electronic density of states for both free-standing and device-configured Fe$_4$GeTe$_2$ (F4GT) confirms its ferromagnetic metallic nature and reveals a weak interface interaction between F4GT and PtTe$_2$ electrodes, enabling efficient spin filtering. We observe a decrease in the magnetic anisotropy energy of F4GT in the device configuration, indicating reduced stability of magnetic moments and heightened sensitivity to external conditions. The transmission eigenstates of PtTe$_2$/ monolayer F4GT/PtTe$_2$ heterostructures demonstrate interference patterns affected by relative phases and localization, notably different in the spin-up and spin-down channels. The ballistic transport through a double-layer F4GT with a ferromagnetic configuration sandwiched between two PtTe$_2$ electrodes is predicted to exhibit an impressive spin polarization of 97$\%$ with spin-up electrons exhibiting higher transmission probability than spin-down electrons. Moreover, we investigate the spin transport properties of Fe$_4$GeTe$_2$/GaTe/Fe$_4$GeTe$_2$ van der Waals heterostructures sandwiched between PtTe$_2$ electrodes to explore their potential as magnetic tunnel junctions (MTJs) in spintronic devices. The inclusion of GaTe as a 2D semiconducting spacer between F4GT layers results in a tunnel magnetoresistance (TMR) of 487$\%$ at low bias and decreases with increasing bias voltage. In general, our findings underscore the potential of F4GT / GaTe / F4GT heterostructures to advance spintronic devices based on van der Waals materials.

cond-mat.mes-hall↗

arXiv2023

Strong in-plane magnetic anisotropy (Co0.15Fe0.85)5GeTe2/graphene van der Waals heterostructure spin-valve at room temperature

Van der Waals (vdW) magnets are promising owing to their tunable magnetic properties with doping or alloy composition, where the strength of magnetic interactions, their symmetry, and magnetic anisotropy can be tuned according to the desired application. However, most of the vdW magnet based spintronic devices are so far limited to cryogenic temperatures with magnetic anisotropies favouring out-of-plane or canted orientation of the magnetization. Here, we report room-temperature lateral spin-valve devices with strong in-plane magnetic anisotropy of the vdW ferromagnet (Co0.15Fe0.85)5GeTe2 (CFGT) in heterostructures with graphene. Magnetization measurements reveal above room-temperature ferromagnetism in CFGT with a strong in-plane magnetic anisotropy. Density functional theory calculations show that the magnitude of the anisotropy depends on the Co concentration and is caused by the substitution of Co in the outermost Fe layer. Heterostructures consisting of CFGT nanolayers and graphene were used to experimentally realize basic building blocks for spin valve devices such as efficient spin injection and detection. The spin transport and Hanle spin precession measurements prove a strong in-plane and negative spin polarization at the interface with graphene, which is supported by the calculated spin-polarized density of states of CFGT. The in-plane magnetization of CFGT at room temperature proves its usefulness in graphene lateral spin-valve devices, thus opening further opportunities for spintronic technologies.

cond-mat.mes-hall↗