arXiv subjects

Jose H. García

Publications and source records attributed to Jose H. García.

5 recordsLinked to original sources

arXiv2025

Spin Polarization driven by Itinerant Orbital Angular Momentum in van der Waals Heterostructures

We report on the possibility of manipulating magnetic materials by using itinerant orbital angular momentum to produce out-of-plane spin polarization in van der Waals heterostructures. Employing a real-space formulation of the OAM operator within linear response theory, we demonstrate that in low-symmetry transition-metal dichalcogenide (TMD) monolayers, such as 1$T{}_d$-MoTe2, the current-induced itinerant OAM exceeds the spin response by three orders of magnitude. When TMDs are coupled with ferromagnets with negligible intrinsic orbital responses, the itinerant OAM generated by the orbital Rashba-Edelstein effect transfers across the interface, generating spin densities capable of inducing magnetization dynamics inside the ferromagnet. Our findings highlight the previously overlooked role of itinerant OAM in the generation of out-of-plane spin densities, which serves as an emerging mechanism for efficient electrical control of magnetization in low-power, ultracompact storage devices.

cond-mat.mes-hall↗

arXiv2024

Orbital Hall Responses in Disordered Topological Materials

We report an efficient numerical approach to compute the different components of the orbital Hall responses in disordered topological materials from the Berry phase theory of magnetization. The theoretical framework is based on the Chebyshev expansion of Green's functions and the off-diagonal elements of the position operator for systems under arbitrary boundary conditions. The capability of this scheme is shown by computing the orbital Hall conductivity for gapped graphene and the Haldane model in the presence of nonperturbative disorder effects. This methodology enables realistic simulations of orbital Hall responses in highly complex models of disordered materials.

cond-mat.mes-hall↗

arXiv2023

Orbital Hall effect and topology on a two-dimensional triangular lattice: from bulk to edge

We investigate a generalized multi-orbital tight-binding model on a triangular lattice, a system prevalent in a wide range of two-dimensional materials, and particularly relevant for simulating transition metal dichalcogenide monolayers. We show that the interplay between spin-orbit coupling and different symmetry-breaking mechanisms leads to the emergence of four distinct topological phases [Eck, P., \textit{et al.}, Phys. Rev. B, 107 (11), 115130 (2023)]. Remarkably, this interplay also triggers the orbital Hall effect with distinguished characteristics. Furthermore, by employing the Landauer-Büttiker formula, we establish that in the orbital Hall insulating phase, the orbital angular momentum is carried by edge states present in nanoribbons with specific terminations. We also show that, as expected, they do not have topological protection against the disorder of the edge states belonging to a first-order topological insulator.

cond-mat.mes-hall↗

arXiv2023

Spin-orbit torque emerging from orbital textures in centrosymmetric materials

We unveil a hitherto concealed spin-orbit torque mechanism driven by orbital degrees of freedom in centrosymmetric two-dimensional transition metal dichalcogenides (focusing on PtSe${}_2$ ). Using first-principles simulations, tight-binding models and large-scale quantum transport calculations, we show that such a mechanism fundamentally stems from a spatial localization of orbital textures at opposite sides of the material, which imprints their symmetries onto spin-orbit coupling effects, further producing efficient and tunable spin-orbit torque. Our study suggests that orbital-spin entanglement at play in centrosymmetric materials can be harnessed as a resource for outperforming conventional spin-orbit torques generated by the Rashba-type effects.

cond-mat.mes-hall↗

arXiv2017

Giant Spin Lifetime Anisotropy in Graphene Induced by Proximity Effects

We report on fundamental aspects of spin dynamics in graphene interfaced with transition metal dichalcogenides (TMDCs). By using realistic models derived from first principles we compute the spin lifetime anisotropy, defined as the ratio of lifetimes for spins pointing out of the graphene plane to those pointing in the plane. In the presence of strong intervalley scattering the anisotropy can reach unprecedented values of tens to hundreds, while it reduces to 1/2 for weak disorder. This behavior is mediated by spin-valley locking, which is strong in TMDCs and is imprinted onto graphene. Such giant spin transport anisotropy, driven by proximity effects, provides an exciting paradigm for designing novel spin device functionalities.

cond-mat.mes-hall↗