Evidence of Ferromagnetic Response of TbMnO$_{3}$ Thin Films at High Temperatures

Abstract

Magnetometry measurements performed on TbMnO$_{3}$ films grown onto single-crystal [001] SrTiO$_{3}$ substrates using magnetron sputtering technique exhibit series of anomalies related to the magnetic ordering of the Mn$^{3+}$ sublattice. Despite the fact that bulk TbMnO$_{3}$ is a low-temperature antiferromagnet, the measurements indicate the presence of high-temperature ferromagnetism. Well-defined hysteresis loops are observed at temperatures as high as 70 K. Analysis of the X-ray diffraction patterns of the target and films shows no evidence of affectation (within the resolution limit of the technique) by external impurities, such as Mn$_{3}$O$_{4}$, which might give rise to an artificial magnetic signal. Thus, it is probable that the ferromagnetism observed in the films to be an intrinsic property of TbMnO$_{3}$. Concretely, it is possible that the strain imposed by the substrate, resulting in the tetragonally distorted orthorhombic phase of the TbMnO$_{3}$ films, is behind the mechanism governing the anomalous ferromagnetism observed in the films.