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Spin injection across heterojunctions plays a decisive role in the new field of spintronics. Within the ballistic transport regime, we state a general expression for the spin-injection rate in a heterojunction made of two ballistic electrodes. Both the spin-orbit interaction and interface scattering effect are taken into account. Our model is consistent with the well-documented results of ferromagnetic-metal junctions. It explains the recent experimental results of a dilute-magnetic-semiconductor/semiconductor junction and predicts solutions to enhance the spin-injection rate across a ferromagnetic-semiconductor junction.

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We investigate the impact of microwave excited spin excitations on the dc charge transport in a ferromagnetic (FM) grating. We observe both resonant and nonresonant microwave photoresistance, which are caused, respectively, by spin and charge dissipations of the microwave power into the FM. A macroscopic model based on Maxwell and Landau-Lifschitz equations reveals the mixing of spin and charge dissipations, which shows that the ferromagnetic anti-resonance is shifted when the conductivity is anisotropic. We find that the microwave photoconductivity provides a powerful new tool to study the interplay between photonic, spintronic, and charge effects in FM microstructures.

We report here the first observation of the cyclotron resonance Landau splitting for low density electron inversion layers in Al Ga& As-GaAs heterojunctions.Even at temperatures close to 100 K electron-electron interactions couple the electrical dipole transitions from the ground and first excited Landau levels, with a coupling strength comparable to the one found at liquid helium temperatures. The experiment can be explained only in a single-particle approximation at sufficiently low densities and/or magnetic field strengths where the resonant polaron effect is important. PACS numbers: 73.20.Dx, 78.20.Ls Cyclotron resonance (CR) in a translational invariant system is a center-of-mass motion and independent of the electron-electron interaction. This famous result, known as Kohn's theorem [1], has been an important guideline

The Raman spectroscopy combined with SVM-RFE opens great future in the clinical applications of mammary disease diagnosis.