Spin-orbit coupling in wurtzite quantum wells

In this work, we derive an effective spin-orbit Hamiltonian for conduction electrons valid for quantum wells, wires, and dots with arbitrary confining potentials and external magnetic fields.
We take into account the s–pz orbital mixing relevant to wurtzite structures (absent in zincblende). Focusing on QWs, we obtain the usual k-linear Rashba term, and differently from
zincblende structures, a bulk Rashba-type term induced by the inversion asymmetry of the wurtzite lattice. Our
results show this latter term to be the main contribution to the Rashba coupling in wurtzite wells. We also find
a k-cubic Dresselhaus contribution. Both the bulk Rashba-type term and this cubic term originate exclusively
from the admixture of s- and pz-like states. Interestingly, in these systems the Rashba and
Dresselhaus Hamiltonians have the same symmetry and can in principle cancel each other out, thus making the
spin a conserved quantity. We then perform a self-consistent calculation on GaN/AlGaN single and
double wells with one and two occupied subbands and determine the intrasubband (intersubband)
Rashba and linear Dresselhaus SO strengths.