We have examined the influence of oxygen-isotope on the pressure effects on the metal-insulator (M-I) transition in La0.65Ca0.35MnO3 (A) and on both the M-I and charge ordering (CO) transitions in La0.57Ca0.43MnO3 (B) under hydrostatic pressures. The pressure was found to enhance Tc at different rates, depending on the O-isotopic mass of the sample. The greater dlnTc/dP observed in the O-18 sample could be understood qualitatively in terms of the double exchange and the band reduction effect of polarons. In the B-samples, the situation is much more complex. Pressure enhances Tc linearly at rates independent of the O-isotopic mass but varies Tco nonlinearly in a complex way. The thermal hysteresis of the CO transition diminishes with increase in pressure suggesting the suppression of the first order CO transition under pressure in both isotopes.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering