Spin-orbit coupling in strained Ge whiskers

The field dependences of the magnetoresistance for germanium whiskers with gallium doping concentration of 2 ⋅ 1017 cm-3 were studied in the magnetic field range 0–14 T at temperature 4.2 K under compressive strain up to 0.2%. The strain influence on a spin-orbit splitting on the valence band spectrum was studied. As a result, the effective mass and the energies of spin-orbit splitting for light and heavy holes were found under the compressive strain according to kp method. From an analysis of the Shubnikov—de Haas magnetoresistance oscillations the effective mass of heavy holes mc = 0.25 m0 was calculated. The spin-orbit splitting energy of heavy holes ΔHH = 15 meV, the Lande factor in direction [111] g* = 4.8 as well as the Rashba cubic parameter of spin-orbit interaction β S O = 1 ⋅ 10 − 28 eV ⋅ m 3 were found due to the studying of longitudinal magnetoconductance in strained Ge whiskers at low temperatures. The appearance of negative magnetoresistance in the magnetic field range up to 7 T likely results from the effect of charge carrier interaction.