High quality Fe3-deltaO4/InAs hybrid structure for electrical spin injection

Single Crystalline Fe3-deltaO4 (0<=delta<=0.33) films have been epitaxially grown on InAs (001) substrates by molecular beam epitaxy using O2 as source of active oxygen. Under optimum growth conditions in-situ real time reflection high-energy electron diffraction patterns along with ex-situ atomic force microscopy indicated the (001) Fe3-deltaO4 to be grown under step-flow-growth mode with a characteristic surface reconstruction. X-ray photoelectron spectroscopy demonstrate the possibility to obtain iron oxides with compositions ranging from Fe3O4 to gamma-Fe2O3. Superconducting quantum interference device magnetometer at 300K shows well behaved magnetic properties giving therefore credibility to the promise of iron based oxides for spintronic applications.Comment: 3 pages, 4 figures appeared in Virtual Journal of Nanoscale Science and Technology, Vol:15, issue12, March 26, 200

Datta-Das type spin-field effect transistor in non-ballistic regime

It is revealed that in spin helix state of (001) quantum well system, strong suppression of D'yakonov-Perel' spin relaxation process occurs by an interplay between Rashba and Dresselhaus couplings over a wide range of Rashba coupling strength. Contrary to common belief in early works, this leads to the finding that Datta-Das type spin-field effect transistor is actually applicable to more realistic non-ballistic transport regime in two dimensional electron gas system.Comment: 8 pages, 3 figure

Cyclotron resonance and mass enhancement by electron correlation in KFe2_2As2_2

Cyclotron resonance (CR) measurements for the Fe-based superconductor KFe$_2$As$_2$ are performed. One signal for CR is observed, and is attributed to the two-dimensional $\alpha$ Fermi surface at the $\Gamma$ point. We found a large discrepancy in the effective masses of CR [(3.4$\pm$0.05)$m_e$ ($m_e$ is the free electron mass)] and de-Haas van Alphen (dHvA) results, a direct evidence of mass enhancement due to electronic correlation. A comparison of the CR and dHvA results shows that both intra- and interband electronic correlations contribute to the mass enhancement in KFe$_2$As$_2$.Comment: 5 pages, 4 figure

Vanishing of inhomogeneous spin relaxation in InAs-based field-effect transistor structures

The D'yakonov-Perel' spin relaxation process in the (001) InAs quantum well system is studied based on Monte Carlo (MC) simulation. The present space-resolved MC analysis demonstrates that the relaxation of spins oriented in any axes is totally suppressed with equal strength of Rashba and Dresselhaus effects, which is in marked contrast with the spin relaxation anisotropy reported previously in time-resolved analyses. Our calculation also shows a substantial contribution of the cubic term of the wave number vector in the Dresselhaus model onto the spatial spin distribution

Evolution of pyramid morphology during InAs(001) homoepitaxy

Growth of InAs(001) homoepitaxial layer has been carried out especially at the bistable region, where the coexistence of both In-stabilized (4x2) and As-stabilized (2x4) surface reconstruction are found to be predominant. The observation of pyramid morphology in this bistable region is reported here. Atomic force microscopy studies have been performed on such pyramids. The heights of the observed pyramids vary from 12 to 26 nm with their bases from 3.6x1.2 to 18x6.3 μm2. Formation of such pyramids in the bistable region is attributed to the unique anomalous As-desorption observed during the surface reconstruction

Micromagnetic simulation of magnetization reversal process and stray field behavior in Fe thin film wire

The magnetization reversal process of Fe thin film wire is studied based on two-dimensional micromagnetic simulation. It is demonstrated that the external field parallel to the width direction results in the formation of a 180 degrees Neel wall, whereas the field applied to the thickness direction yields the Bloch-like walls, which turn into C-type walls in the residual state. These behaviors are explained by the anisotropic dependence of wall energy in the direction of the external field. The stray field during this process is analyzed in detail

Thermodynamic Calculation of Phase Equilibria in As-Fe-In Ternary System Based on CALPHAD Approach

Thermodynamic calculation of phase equilibria in As-Fe-In ternary system is performed based on Calphad approach, directing a special attention to fabrication process of Fe/InAs hybrid structure for spin injection device. For this, the thermodynamic assessment of Fe-In binary system is first carried out utilizing reported experimental data. Then, the liquidus surface of the ternary system and invariant reactions are calculated. The isothermal sections in low temperature region are presented and discussed in the light of the optimization of the growth temperature of Fe film on InAs substrate during the fabrication process