The pressure dependence of the resistivity and structure of ${\mathrm{La}}_{0.60}{\mathrm{Y}}_{0.07}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_3$ has been explored in the pressure range from 1 atm to ∼7 GPa. The metal to insulator transition temperature ${(T}_{\mathrm{MI}})$ was found to reach a maximum and the resistivity achieves a minimum at ∼3.8 GPa. Beyond this pressure, $T_{\mathrm{MI}}$ is reduced with a concomitant increase in the resistivity. Structural measurements at room temperature show that at low pressure (below 2 GPa) the Mn-O bond lengths are compressed. Between ∼2 and ∼4 GPa, a pressure-induced enhancement of the Jahn-Teller (JT) distortion occurs in parallel with an increase in Mn-O1-Mn bond angle to ∼180°. Above ∼4 GPa, the Mn-O1-Mn bond angle is reduced, while the JT distortion appears to remain unchanged. The resistivity above $T_{\mathrm{MI}}$ is well modeled by variable range hopping. The pressure dependence of the localization length follows the behavior of $T_{\mathrm{MI}}.$

• Received 2 December 2002

DOI:https://doi.org/10.1103/PhysRevB.67.104107