Spin properties of Hg_1–xCd_x Te/CdTe quantum wells

Abstract

IntroductionThe effect of the spin-orbit (SO) interaction on a free charge carrier spin in semiconductors is twofold. First of all, it reorders the band structure at the center of the Brillouin zone, a typical example being the valence band rearrangement in elementary and compound semiconductors and appearance of new, SO split-off band. Secondly, the SO interaction lifts off the spin-splitting in otherwise degenerate energy bands, for example of the doubly degenerate Kramers pairs, if a semiconductor lattice or QW does not possess the inversion symmetry. This is a typical situation found in A 3 B 5 and A 2 B 6 compounds. Usually the former effect is much stronger than that of the spin-splitting of Kramers pairs. Typical values of the spin-orbit split-off energy D lie in the range of 0.1-1 eV [1], while the degenerate band spin-splitting energies are of the order of 0.01 eV for room temperature free charge-carriers [2,3]. The rearrangement of the energy bands and appearance of D is also reflected in carrier spin properties too: the average spin magnitude of the free carrier begins to depend on spin direction and magnitude of the wave vector [4].In the inverted band semiconductors represented by HgTe the energy gap g E has a negative value. The branches of conduction band dispersion in these semiconductors are directed downwards and merge with the valence band continuum. The role of the conduction band is

Valence Band of Cubic Semiconductors from Viewpoint of Clifford Algebra

“…The typical representatives are A 3 B 5 compounds, the valence band of which is described by the Luttinger-Kohn Hamiltonian [6]. In papers [7][8][9] the hole spin properties were analyzed in a standard manner within the Hilbert space, either using unitary matrices, or commutators to describe nontrivial * e-mail: dargys@pfi.lt free-hole spin precession properties. Here the problem will be treated within Clifford algebra formalism that is related to SO(5) symmetry group.…”

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

“…The shape of the spin surface depends on QW composition [36] and free carrier wave vector but is independent of a particular SO interaction mechanism used (Rashba or QW asymmetry in electric field). In 2D conduction subbands, the spherical shape is preserved only for high energy electrons.…”

Abnormal physics of group-IItelluride system: valence contribution of d electrons

“…In addition, the heterostructures based on group-II telluride compounds also exhibit different properties from the conventional common-anion semiconductors. For instance, the CdTe/HgTe superlattice has a large valence-band offset, [11,12] which is unable to be answered from the recognized common-anion rule, predicting nearly vanishing valence-band offsets for most common-anion semiconductors. The physics of the group-II telluride system is fascinating but also challenging.…”