Pressure effects on the metal-insulator transition in magnetoresistive manganese perovskites

Quasi-hydrostatic-pressure measurements of electrical resistivity up to 11 kbar are presented for a series of manganese perovskites L(2/3)A(1/3)MnO(3). It is found that the Curie temperature T-C, being itself a function of the electronic bandwidth W, displays a larger variation of d ln T-C/dP as the bandwidth is reduced. It is shown that this effect arises primarily from the Mn-O-Mn bond stretching under pressure. However, the observed d ln T-C/dP versus T-C or W variations are found to be significantly larger than expected on the basis of simple steric modifications of bandwidth. We suggest that the electron-phonon coupling is substantially reduced under pressure; this effect is more prominent as the bandwidth is reduced. [S0163-1829(97)51940-0].