S.G. Zhao

Photoinduced effect in charge-ordering La0.5Ca0.5MnO3 film

Charge-ordered La0.5Ca0.5MnO3 film has been deposited on (100)-LaAlO3 substrate using rf magnetron sputtering method. X-ray diffraction analysis shows that the bulk has orthorhombic structure and the film has the better epitaxial character. The charge-ordering transition temperature is about 280 K by fitting the resistance-temperature curve using the variable-range hopping model. The decrease in the resistance of the film irradiated by the laser is caused by the delocalization effect of the correlated electron system. The photoinduced relaxation exhibits different processes when the laser is on and off, which can be attributed to thermal fluctuation.

Electrical transport and photoinduced properties of an Sr0.7Ce0.3MnO3 film

Direct current (dc) electrical transport and photoinduced properties of a high-quality epitaxial film of Sr0.7Ce0.3MnO3 on a (100)-oriented LaAlO3 substrate have been investigated. The sample exhibits semiconductive behavior and the electrical transport result agrees with Motts VRH model. Laser irradiation results in a decrease of the resistance of the film in the entire temperature range measured, which is attributed to the photogenerated electron–hole pairs and the electron hopping from the valence band to the conduction band.

Photoinduced characteristics in La0.67Sr0.33Mn0.95Zn0.05O3 film

La0.67Sr0.33Mn0.95Zn0.05O3 film has been deposited on LaAlO3 (100) substrate by the magnetron sputtering method. The results concerning the photoinduced character of the film are reported. In the ferromagnetic metallic state, the increasing photoinduced resistance is caused by photoinduced demagnetization of the spin correlation system in manganites. The photoinduced relaxation character of the film indicates that the time constant increases with increasing temperature, which is attributed to the thermal fluctuation.

Transport and transient photoconductivity in La0.85Sr0.015MnO3–δ/Fe heterostructure

La0.85Sr0.015MnO3–δ (LSMO)/Fe heterostructure has been deposited on Si (100) substrate by magnetron sputtering. The results concerning the heterostructure in current perpendicular-to-plane geometry are reported. The sample exhibits a semiconductor-type conduction as the temperature is increased. Laser irradiation induces transient photoconductivity effects. These can be attributed to the disordered characteristic due to the oxygen deficiency in the film and the interface between the Fe and LSMO.

Transport properties in the La0.8Sr0.2MnO3/Co heterostructure

The transport properties of the La0.8Sr0.2MnO3/Co heterostructrue prepared by the sol-gel method were investigated. The results about the heterostructure in the current-perpendicular-to-plane geometry are reported. The sample exhibits the semiconductor-type conduction as the temperature is increased. The formed interface is the Schottky barrier and the dominant transport is the quasiparticle tunnelling via a pair of localized states due to the space-charge limits rule.