Energy Surfaces and Domain Structure of Pb1-xGexTe in the Rhombohedral Phase

The band edge structures of p -Pb 1- x Ge x Te are studied by measuring the quantum oscillations of the sound velocity and the RF-surface impedance for five different values of x at 1.4 K. The angular dependences of the periods become more complicated as x increased. This could be related to the valley-splittings due to the phase transition. For the large value of x ( x ≃0.028), the extra branches of the periods appear clearly which could be explained by taking account of the domain structure in the rhombohedral phase. The order parameter of the phase transition is determined as a function of the transition temperature. The values of the optical and shear deformation potential constants are determined to be \(\varXi = (16.8 \pm 1.0)\) eV and D a v = (11.7 ±1.0) eV, respectively.