Xingmin Liu

The nonlinear Rashba effect in Hg0.77Cd0.23Te inversion layers probed by weak antilocalization analysis

The Rashba spin-orbit interaction of the two-dimensional electron gas with high mobility in the inversion layer of p-type Hg0.77Cd0.23Te is investigated by magnetotransport measurements. Both the Rashba spin splitting and Rashba coefficient are extracted by analysis of the weak anti-localization effect using the Golub model. It is found that both the splitting and coefficient increase with increasing electron density (∼3.0–6.0u2009×u20091015u2009m−2), i.e., with the gate voltage. A self-consistent Schrodinger-Poisson calculation is performed and suggests that the nonlinear Rashba effect caused by the weakening of interband coupling, especially at high electron density, dominates this system.

Design and fabrication of Dy-free sintered permanent magnets with high coercivity

The purpose of this study was to save heavy rare earth Dy in NdFeB production. By ways of optimizing preparation process and replacing Nd with Pr, Dy-free magnet with high coercivity was successfully prepared, the nominal composition is Pr14B6Co2.2Cu0.2Al1Fe76.7 (at %). The effect of Pr on magnetic performance and microstructure of the magnet were investigated systemically, alloy Nd13.65B6Co2.2Cu0.2Al1Fe76.9 (at %) was prepared by the same preparation process as comparison. The results indicated that magnet Pr14B6Co2.2Cu0.2Al1Fe76.7 has much higher coercivity than that of magnet Nd13.65B6Co2.2Cu0.2Al1Fe76.9. Microstructure investigation showed that the presence of small grains, thin and smooth RE-rich film, associated with higher coercivity.

Effect of Strip Casting on Microstructure and Magnetic Properties of 2:17 Type Sm-Co Sintered Magnets

The 2:17 type Sm-Co sintered magnets were made with strips and ingots, separately. The phase structure and microstructure of the cast alloys and their effects on magnetic properties of the magnets have been comparatively studied. X-ray diffraction analysis shows that the phase structure of strips and ingots both consist of TbCu7-type phase with a little CaCu5-type phase. Scanning electron microscopy research shows that the microstructure of strips is composed of dendritic crystal grains which are larger than 10 μm in cross section and less than 4 μm in the free side, whereas, the grain size of ingots is larger than 40 μm. Higher remanence and maximum magnetic energy product are observed in magnets made with ingots (IM) than that made with strips (SM), which is due to low grain alignment degree of the magnets made with strips. In order to increase the grain alignment degree of magnets made with strips, the powder particle size has been reduced. Fruitfully, the remanence and the maximum energy products gradually increase with decreasing the powder particle size.

Spin dependence of electron effective masses in InGaAs/InAlAs quantum well

The effective masses for spin-up and spin-down electrons of a partially spin-polarized Fermi liquid are theoretically expected to be different. We extract the spin-up and spin-down effective masses from magnetotransport measurements at different temperatures for a two-dimensional electron gas in an In0.65Ga0.35As/In0.52Al0.48As quantum well exhibiting zero-field spin splitting. We apply two analytical methods, one involving the simultaneous fitting of fast Fourier transform (FFT) spectra and the other involving inverse FFT analysis. Both methods confirm that the effective masses for spin-up and spin-down are different, consistent with theoretical expectations.