Spin texture and Berry phase for heavy-mass holes confined in SiGe mixed-alloy two-dimensional system: Intersubband interaction via the coexistence of Rashba and Dresselhaus spin-orbit interactions

By extending the k⋅p approach, we study the spin texture and Berry phase of heavy-mass holes (HHs) confined in the SiGe two-dimensional (2D) quantum well system, focusing on the intersubband interaction via the coexistence of the Rashba and Dresselhaus spin-orbit interactions (SOIs). The coexistence of both SOIs generates spin-stabilized(+)/destabilized(-) HHs. The strong intersubband interaction causes quasi-degenerate states resembling the 2D massive Dirac fermion. Consequently, the Berry phases of HHs have unique energy dependence understood by counting the quasi-degenerate points with the signs of the Berry phases. Thermal averaging of the Berry phase demonstrates that HH+/− has a peculiar plateau of +π/−π at less than 30 K and then changes its sign at approximately 200 K.