Thermopower and electrical resistivity of La0.875Sr0.125MnO3 single crystals under hydrostatic pressure

The thermopower α and the electrical resistivity ρ of La_1?x Sr_xMnO₃ single crystals with a strontium content x=0.125, which corresponds to the stoichiometric composition of the new charge-ordered (CO) phase, are measured in the temperature range 77–300 K at pressures up to 12 kbar. The dependence α(T) exhibits two maxima. The first low-temperature maximum is associated with the formation of the charge-ordered phase. The second high-temperature maximum is attributed to the O → O′ structural transition between the orthorhombic phases and the formation of ferromagnetic clusters. It is found that the phase transition observed at P>9.2 kbar is accompanied by a substantial shift of both maxima toward the low-temperature range.