MAGNETORESISTANCE OF HGSES CRYSTALS AT HYDROSTATIC PRESSURES OF UP TO1 GPA

Magnetoresistance (MR) of HgSe1-xSx crystals has been studied in the t emperature range 4.2-300 K and in magnetic fields up to 12 T under hyd rostatic pressures P exceeding the threshold P-t for the structural ph ase 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, wh ich presumably incorporate the high- and low-pressure phases, and in w hich the oscillations vanished. At the same time the monotonic behavio r of MR with magnetic field B, as well as the temperature dependences of resistivity rho retained the shape characteristic of the original p hases. 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 metast able states. It is the corresponding decrease of electron mobility tha t suppresses the oscillations. (C) 1997 American Institute of Physics.