Effect of Strain on the Transport Properties of the Manganite

Abstract

The effect of strain on the resistivity and thermopower of ferromagnetic manganites has been examined based on the model that incorporates the electron-lattice interaction through the Jahn-Teller effect and an effective hopping determined by nearest neighbor spin-spin correlation of t 2g electrons. The metal insulator transition temperature associated with resistivity decreases with increase in strain. In the presence of large strain the system remains in the semiconducting state. Thermopower (S) is positive and increasing function of strain and it exhibits a maximum with temperature. The temperature where maximum of S appears, shifts towards higher (lower) value in the presence of magnetic field (strain). A large magneto-thermopower that depends on strain is obtained around metal-insulator transition.

The effect of band Jahn–Teller distortion on the magnetoresistivity of manganites: a model study

“…The field dependence of m c and e for different temperatures is reflected in the temperature dependence of the magnetoresistivity, which is shown in figure 6(b). With increasing magnetic field, the resistivity peak is suppressed considerably, exhibiting the tendency observed for colossal magnetoresistance as shown in several experimental measurements [3,19,22,31,32]. It can be seen here that the resistivity is independent of magnetic field in the high temperature paramagnetic phase.…”

“…It is observed that the resistivity becomes very high in the pure JT distorted phase near the Curie temperature of the manganite system separating the ferromagnetic metallic phase at low temperatures and the paramagnetic phase at higher temperatures, as observed in several experiments [12,31,32,34,35]. The resistivity attains a minimum value at the Curie temperature as the temperature is lowered, then increased slowly and is finally suppressed at still lower temperatures, indicating the ferromagnetic metallic phase of the system [12,[16][17][18][19]. With increasing magnetic field, the resistivity peak is suppressed considerably, exhibiting the tendency observed for the CMR effect in manganites.…”

“…For electron-doped Sr 1−x Ce x MnO 3 (x = 0.1), a jump in the resistivity peak at T ∼ 315 K due to JT ordering is observed from neutron and electron diffraction studies [18]. A large number of studies on manganite systems signify the presence of the metal-insulator transition (MIT) because of competition between the ferromagnetic metallic state due to the DE interaction and the insulating phase due to the JT distortion [12,[19][20][21][22]. Recently, Rout et al have reported the theoretical investigations of the effect of charge ordering on the physical properties like magnetisation [23], velocity of sound [24], magnetic spin susceptibility [25] and Raman spectra [26] for the manganite system.…”