Enhanced electron-lattice coupling in La1-xSrxMnO3 near the metal-insulator phase boundary

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