Spin properties of free electrons and holes in Hg1-xCdxTe/CdTe quantum well

Spin properties of Hg1-xCdxTe/CdTe quantum wells (QW) with inverted energy bands are considered using eight-band k.p Hamiltonian. The spin splitting of doubly degenerate bands (Kramers pairs) was included via either Rashba or external voltage Hamiltonians. The spin surfaces, which describe the average spin as a function of spin direction of a ballistic 2D charge carrier, in general, are shown to be ellipsoidal rather than spherical. In extreme cases the spin surfaces may reduce to disk, line, or Bloch sphere. Characteristic shapes of the spin surfaces at different wave vectors and QW composition x are presented in a form of graphs in the spin space.