arXiv subjects

Darius-Alexandru Deaconu

Publications and source records attributed to Darius-Alexandru Deaconu.

4 recordsLinked to original sources

arXiv2026

Strain Tuning of Orbital-Driven Giant Magnetoresistance in van der Waals ferrimagnet Mn$_3$Si$_2$Te$_6$

Strain engineering of magnetotransport offers a powerful strategy for uncovering emergent electronic and domain phenomena in quantum magnetic materials, while providing a promising pathway toward next-generation mechanically programmable spintronic technologies. Van der Waals magnets are particularly attractive in this context because their high crystallinity and mechanical flexibility allow exceptionally large, precisely controllable strain, enabling access to strain-induced functionalities unattainable in conventional solids. Here, we report systematic strain control of the van der Waals magnet Mn$_3$Si$_2$Te$_6$, which exhibits an unconventional colossal magnetoresistance whose microscopic origin remains under debate. We demonstrate in situ large-strain modulation of the electrical resistance in bulk crystals and show that the effect can be consistently explained by strain-tunable chiral orbital-current domains. Furthermore, measurements on exfoliated flake devices containing a single chiral domain reveal direct strain control of the electronic structure affected by orbital magnetic moment, establishing a unified microscopic mechanism for the unconventional colossal magnetoresistance. These results identify strain as an exceptionally effective control parameter for tailoring electronic and magnetic states in van der Waals magnets and provide a conceptual framework for realizing spin-straintronic functionalities based on orbital degrees of freedom.

cond-mat.mtrl-sci↗

arXiv2025

Magnetic resonance and microwave resistance modulation in van der Waals colossal-magnetoresistance material

Colossal magnetoresistance (CMR) is a fascinating quantum phenomenon that continues to draw significant interest in condensed matter physics. Mn3Si2Te6 has emerged as a prototypical CMR material, notable for its puzzling magnetoresistance behavior and pronounced directional anisotropy. Despite extensive research, the mechanisms driving CMR in Mn3Si2Te6 remain elusive [1-4]. In this work, we explore the magnetic resonance of Mn3Si2Te6 and observe a reduced g-factor for magnetic fields applied along the crystalline c-axis compared to the ab-plane, indicating a substantial orbital magnetization contribution along the c-axis. Furthermore, we detect resistance modulation under resonance conditions, suggesting that CMR in Mn3Si2Te6 is sensitive to the out-of-the plane spin polarization. These findings shed new light on the role of orbital magnetic moment in Mn3Si2Te6, offering a deeper understanding of the interplay between spin, orbital and lattice degrees of freedom of electrons in this system.

cond-mat.mtrl-sci↗

arXiv2025

Field-driven band asymmetry and non-reciprocal transport in a helimagnet

Helimagnets exhibit noncollinear spin arrangements characterized by a periodic helical modulation, giving rise to emergent chiral properties. These materials have attracted significant interest due to their potential applications in spintronics, particularly for robust information storage and the realization of topological spin textures such as skyrmions. In this work, we focus on Yoshimori-type helimagnets, where competing exchange interactions mediated by conduction electrons stabilize helical spin structures without requiring Dzyaloshinskii-Moriya interaction. We introduce a minimal model describing the electronic structure of a one-dimensional helimagnet in the presence of an external magnetic field and investigate its impact on non-reciprocal transport. We demonstrate how band asymmetry emerges in the conical phase induced by the external field, leading to a nonzero second-order electronic conductivity and injection photoconductivity. Our results provide insight into the interplay between the real space magnetic texture and electronic properties, paving the way for future studies on chirality-driven transport phenomena in centrosymmetric helimagnets.

cond-mat.mes-hall↗

arXiv2024

Band-asymmetry-driven nonreciprocal electronic transport in a helimagnetic semimetal α-EuP$_3$

Chiral magnetic textures give rise to unconventional magnetotransport phenomena such as the topological Hall effect and nonreciprocal electronic transport. While the correspondence between real-space magnetic topology/symmetry and such transport phenomena has been well established, a microscopic understanding based on the spin-dependent band structure in momentum space remains elusive. Here we demonstrate how a chiral magnetic structure in real space introduces an asymmetry in the electronic band structure and triggers a nonreciprocal electronic transport in a centrosymmetric helimagnet α-EuP$_3$. The magnetic structure of α-EuP$_3$ is highly tunable by a magnetic field and closely coupled to its semi-metallic electronic band structure, enabling a systematic study across chiral and achiral magnetic phases on the correspondence between nonreciprocal transport and electronic band asymmetry. Our findings reveal how a microscopic change in the magnetic configuration of charge carriers can lead to nonreciprocal electronic transport, paving the way for designing chiral magnets with desirable properties.

cond-mat.mtrl-sci↗