Effects of phase transition driven by cation vacancies on magnetism and electricity in LaxMnO3 thin films

Abstract

The attractive physical properties of perovskite manganese make them fundamental building blocks for oxide spintronic devices. However, defects and lattice distortions can lead to extrinsic properties, especially cation vacancies, severely compromising device performance. In particularly, many intriguing properties, such as the emergence of magnetism and two-dimensional high-mobility electron gases, are closely related to cation vacancies. In this study, we deposited a series of LaxMnO3 epitaxial thin films with varying contents of La3+ vacancies on SrTiO3 (100) substrates, with the presence of La3+ vacancies verified by using X-ray diffraction, X-ray photoemission spectroscopy, X-ray absorption spectroscopy, and energy dispersive spectroscopy spectrum. The reduction in La3+ vacancies led to stronger ferromagnetism with an easy axis oriented along the (110) direction in LaMnO3 thin films, along with the appearance of a monoclinic phase, indicating that the ferromagnetism possibly originated from the three-dimensional d3z2−r2/dx2−y2-alternated orbital order rather than the Mn3+/Mn4+ double exchange effect. This result implies that the consistent regulation of cation vacancies by pulsed laser deposition can modulate both the structure and physical properties of manganate films, thereby enabling control over device properties.