Magnetoresistance of HgSeS crystals at hydrostatic pressures of up to 1 GPa

Magnetoresistance (MR) of HgSe1-xSx crystals has been studied in the temperature range 4.2-300 K and in magnetic fields up to 12 T under hydrostatic pressures P exceeding the threshold P-t for the structural phase transition. Shubnikov-de Haas quantum oscillations in longitudinal and transverse MR were observed to occur in the original samples at T=4.2 K. For P>P-t, HgSeS crystals transferred to metastable states, which presumably incorporate the high- and low-pressure phases, and in which the oscillations vanished. At the same time the monotonic behavior of MR with magnetic field B, as well as the temperature dependences of resistivity rho retained the shape characteristic of the original phases. The observed weakening of the dependences of rho on B and T is attributed to an increase of the temperature-independent contribution to rho caused by phase inclusions and structural defects in the metastable states. It is the corresponding decrease of electron mobility that suppresses the oscillations. (C) 1997 American Institute of Physics.