Electronic Excitation-Induced Modification in Electronic Structure and Magnetism for Pulsed Laser Deposited Barium Strontium Titanate Thin Films with Changing Fe Impurity

TL;DR

This study explores how electronic excitation affects the electronic structure and magnetism of barium strontium titanate thin films with varying iron impurity levels.

Contribution

The paper introduces a novel approach to modulate ferromagnetism through electronic excitation and Fe impurity engineering in thin films.

Findings

Irradiation reduces grain height and increases oxygen vacancy concentration with higher fluence.

Ferromagnetism deteriorates as irradiation fluence increases due to cation interstitial defects.

Electronic excitation disrupts magnetic polarons, degrading long-range ferromagnetism.

Abstract

This study presents a comprehensive analysis of the modifications in electronic structure and magnetism resulting from electronic excitation in pulsed laser-deposited Ba0.7Sr0.3FexTi(1−x)O3 thin films, specifically for compositions with x = 0, 0.1, and 0.2. To investigate the effects of electronic energy loss (Se) within the lattice, we performed 120 MeV Ag ion irradiation at varying fluences (1 × 1012 ions/cm2 and 5 × 1012 ions/cm2) and compared the results with those of the pristine sample. The Se induces lattice damage by generating ion tracks along its trajectory, which subsequently leads to a reduction in peak intensity observed in X-ray diffraction patterns. Atomic force microscopy micrographs indicate that irradiation resulted in a decrease in average grain height, accompanied by a more homogeneous grain distribution. X-ray photoelectron spectroscopy reveals a significant increase in oxygen vacancy (VO) concentration as ion fluence increases. Ferromagnetism exhibits progressive deterioration with rising irradiation fluence. Due to the high Se and multiple ion impact processes, cation interstitial defects are highly likely, which may overshadow the influence of VO in inducing ferromagnetism, thereby contributing to an overall decline in magnetic properties. Furthermore, the elevated Se potentially disrupts bound magnetic polarons, leading to a degradation of long-range ferromagnetism. Collectively, this investigation elucidates the electronic excitation-induced modulation of ferromagnetism, employing Fe impurity incorporation and irradiation techniques for precise defect engineering.

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