Ferromagnetism, insulator-metal transition and magnetotransport in Pr0.58Ca0.42MnO3 films: role of microstructural perturbations

TL;DR

This study investigates how microstructural differences in Pr0.58Ca0.42MnO3 films, caused by growth environment, influence their magnetic, insulator-metal transition, and magnetotransport properties, revealing the role of disorder and defects.

Contribution

It demonstrates that microstructural perturbations significantly affect magnetic transitions and insulator-metal behavior in Pr0.58Ca0.42MnO3 films, highlighting the impact of growth conditions.

Findings

Air-annealed film shows charge order quenching and ferromagnetic transition at 148 K.

Oxygen-annealed film exhibits charge order, ferromagnetic, and antiferromagnetic transitions with different IMT behavior.

Magnetic field influences transition temperatures, hysteresis, and resistivity jumps, with effects more pronounced in oxygen-annealed films.

Abstract

Magnetic and magnetotransport properties of oriented polycrystalline Pr0.58Ca0.42MnO3 thin films prepared in flowing oxygen and air ambient has been investigated. The magnetic ground state of both the films is a frozen cluster glass. In the air annealed film charge order (CO) is quenched and ferromagnetic (FM) transition, which appears at TC=148 K is followed by antiferromagnetic (AFM) transition at TN=104 K. This film shows self-field hysteretic insulator-metal transition (IMT) at TIMC=89 K and TIMW=148 K in the cooling and warming cycle, respectively. Application of magnetic field (H) gradually enhances TIMC and TIMW, reduces the thermoresistive hysteresis and TIM diminishes. In contrast, the film annealed in flowing oxygen shows a CO transition, which is followed by FM and AFM transitions. This film shows appreciably smaller magnetic moment and does not show IMT upto H=20 kOe. As H is increased to H=30 kOe, IMT having strong thermoresistive hysteresis and sharp resistivity jumps appears in the cooling and warming cycles. As H increases to higher values the thermoresistive hysteresis is reduced, resistivity jumps are observed to disappear and TIM decreases. In the lower temperature regime the resistivity first decreases slowly with H and then shows sharp drop. The virgin cycle is not recoverable in subsequent cycles. The decrement far more pronounced in the oxygen annealed film and occurs at much higher H suggesting that the frozen cluster glass state is more robust in this film. The microstructural analysis of the two set of films shows CO quenching, FM transition and self-field IMT in air annealed film is caused by higher density of microstructural disorder and lattice defects. The difference in growth ambience of the two films could give rise to such microstructural perturbations.