X-ray diffraction study of Zn0.9Co0.1S under high pressure

Dilute magnetic semiconductors (DMS) form a class of semiconducting materia ls obtained by substituting a fraction of cations with a magnetic ion, e.g. Zn0.9Co0.1S. These alloys exhibit a variety of novel magneto-optical prope rties coming from the exchange interaction between the magnetic ions and th e conduction or valence electrons (s-p exchange interaction). This interact ion is increased at high pressure and may induce phase transitions. In this paper, Zn0.9Co0.1S has been studied under high pressure up to 28 GPa. At a mbient conditions it crystallizes in the sphalerite structure with the same lattice parameter as ZnS. At high pressure the most intense peaks of the b lende phase have been observed up to 17 GPa, but new peaks appear above 12. 7 GPa. The new peaks have been indexed in a disordered rock-salt phase. Thi s phase is stable at least up to 28 GPa (maximum pressure reached in this e xperiment). The unit cell volume has been fitted with a first-order Murnagh an equation of state. The deduced bulk moduli are B = (84 +/- 2) GPa in the zincblende phase and B = (119 +/- 16) GPa in the NaCl phase, with B' = 4 i n both cases. The recovered phase is identical to the initial phase at 0 GP a.