ENHANCED ELECTRON-LATTICE COUPLING IN LA1-XSRXMNO3 NEAR THE METAL-INSULATOR PHASE-BOUNDARY

Effects of hydrostatic pressure on the magnetic and transport properti es have been investigated for melt-grown crystals of La1-xSrxMnO3 with a finely-controlled doping level x near the metal-insulator phase bou ndary. Application of pressure affects the critical temperatures for t he orthorhombic-rhombohedral structural transition (T-s) as well as fo r the metal-insulator transition (T-MI) that has been interpreted in t erms of an ordering of the Jahn-Teller polarons. Reflecting that the k inetic energy of the e(g) carriers sensitively depends on the degree o f the lattice distortion, T-s shows an abrupt decrease under pressure when it crosses the magnetic phase boundary. On the other hand, T-MI i s significantly suppressed under pressure via enhanced e(g)-electron h opping. These pressure effects are compared with those of an external magnetic field.