Thermodynamic elastic-strain mechanism controlling the dynamics of properties and phase states in magnetic semiconductors

摘要

The effects of high hydrostatic pressure, magnetic field, and temperature on the dynamics of electric resistance are studied in the ceramic and film samples of La{sub}0.56Ca{sub}0.24Mn{sub}1.2O{sub}3 and La{sub}0.7Mn{sub}1.3O{sub}3. It is found that the same variations of the sample conductivity are observed in response to equivalent changes in the temperature (by 6.4 K), magnetic field strength (2.4 kOe), or hydrostatic pressure (1 kbar). An analysis of the experimental data allows a thermodynamic mechanism accounting for the elastic anisotropic straining and determining the dynamics of properties and phase states in the magnetic semiconductors to be established. The baroresistance and baromagnetoresistance effects are revealed. The magnetoelastic-strain mechanism of realization of the giant magnetoresistance effect is outlined.