Searcharxiv⌕ Search

arXiv subjects

Arles V. Gil Rebaza

Publications and source records attributed to Arles V. Gil Rebaza.

3 recordsLinked to original sources

Theoretical spin transport analysis for a spin pseudovalve-type $\mathrm{L}_j$/semiconductor/$\mathrm{L}_j$ trilayer (with $\mathrm{L}_j$ = ferromagnetic)

In this work, a theoretical study of spin transport in a pseudovalve spin (PSV) heterostructure is conducted. For the semiconductor (SC), the conduction band at the $Γ$ point of reciprocal space and spin-orbit coupling (SOC) are considered. For the ferromagnetic (FM) electrodes on the left ($l$) and right ($r$), the internal exchange energy ($Δ_j$, where $j = \left(l,r\right)$) and the magnetization normal vector ($\mathbf{n}_j$) on the barrier plane are taken into account. An analytical expression for the transmission probability as a function of $\mathbf{n}_j$ direction was obtained from the {\em Schrödinger-Pauli} equations with the boundary conditions. Furthermore, the tunnel magnetoresistance (TMR) at T $\approx$ 0 K was calculated, depending on the direction of the crystallographic axis favoring the magnetization ($θ_m$) of the FM and the thickness of the SC, using the {\em Landauer-Büttiker} formula for a single channel. It is observed that the TMR reaches its maximum value when the $\mathbf{n}_l$ direction is parallel to $θ_m$. Applying this physico-mathematical model to the Fe/SC/Fe PSV, with SC as GaAs, GaSb, and InAs, it was found that the {\em Dresselhaus} SOC does not significantly contribute to the TMR.

cond-mat.mtrl-sci↗

Spin transport analysis for a spin pseudovalve-type L_l/SC/L_r trilayer for L = {FeCr, Fe, Co, NiFe, Ni} and SC = {GaSb, InSb, InAs, GaAs, ZnSe}

In this work, we present a theoretical study of spin transport in a trilayer pseudospin-valve (PSV) heterostructure composed of electrode (L_l)/insulator/electrode (L_r). The insulating layer corrresponds to a semiconductor (SC) with a zinc-blende crystal structure from the III-V (GaSb, InSb, InAs, and GaAs) or the II-VI (ZnSe), while the electrodes are ferromagnetic materials L_j = {FeCr, Fe, Co, NiFe, Ni}. This combination yields 125 possible PSV configurations. The theoretical model implemented is based on the approach proposed by J. C. Slonczewski. In our approach, the exchange splitting in the ferromagnetic materials and the spin-orbit coupling (SOC) of the Dresselhaus and Rashba types in the semiconductors are included, allowing control of the wave vector associated with the spin states. The tunnel magnetoresistance (TMR) is calculated at low temperature as a function of the semiconductor thickness, parameterized with respect to the crystallographic axis that favors the magnetization direction in the ferromagnetic electrodes, within the Landauer--Büttiker formalism in the single-channel regime. The results show that the TMR reaches its maximum value independently of the relative orientation between the magnetization vector and the crystallographic direction. The most efficient configuration corresponds to Fe_{90}Cr_{10}/GaSb/Fe_{90}Cr_{10}, with a TMR value of 83.60%. Furthermore, the Dresselhaus SOC contributes more significantly to the TMR than the Rashba SOC. Finally, the TMR varies when the electrodes L_j are permuted, due to differences in their Fermi energies. The obtained results are compared with previous studies reported in the literature based on alternative theoretical frameworks or assumptions, showing good agreement.

cond-mat.mes-hall↗

Ab-initio approach to the stability and the structural, electronic and magnetic properties of the (001) Znfe2O4 surface terminations

We present a Density Functional Theory (DFT) based study of the structural and magnetic properties of the (001) surface of the semiconducting oxide ZnFe2O4 (spinel structure). The calculations were performed using the DFT based ab initio plane wave and pseudopotential method as implemented in the Quantum Espresso code. The all electron Full-potential linearized-augmented-plane-wave method (FP-LAPW) was also employed to check the accuracy of plane wave method. In both calculations the DFT+U methodology was employed and different (001) surface terminations of ZnFe2O4 were studied: We find that the surface terminated in Zn is the stable one. For all the (001) surface terminations our calculations predict that the Zn-Fe cationic inversion (antisites), which are defects in bulk ZnFe2O4, becomes stable and an integral part of the surface. Also, a ferrimagnetic behavior is predicted for the case of antisites in the superficial layer. Our results for different properties of the surface of ZnFe2O4 are compared with those obtained in bulk samples and those reported in the literature.

cond-mat.mtrl-sci↗