TGGM designed the experiments and co-wrote the manuscript. All authors have read and approved the final manuscript.”
“Background Due to its low resistivity and good chemical stability, SrRuO3 (SRO) is frequently used as metallic electrodes in epitaxial perovskite-heterostructure
capacitors [1, 2]. Film thickness, the amount of lattice mismatch, oxygen vacancy, and Ru vacancy are found to change its physical properties. Fundamental thickness limit of itinerant ferromagnetism was observed [3]. In addition to thickness being smaller than the critical thickness (t < 10 unit cells), a significant amount of oxygen vacancy was also found to deteriorate its ferromagnetic Selleck MAPK inhibitor properties for thicker films (t > > 10 unit cells). Aside from these two factors, the ferromagnetic properties of SRO, especially the ferromagnetic transition temperature, T c, have been known to be rather robust.
While transport properties such as residual resistivity ratio VS-4718 mouse (varying order of magnitude) are very sensitive to a tiny amount of Ru vacancy in SRO thin films grown on (100) SrTiO3 (STO) substrates, the ferromagnetic properties are rather immune to this tiny amount of Ru vacancy [1]. A peculiar orthorhombic-to-tetragonal structural transition with variation of the Ru-O-Ru bond angle was observed depending on the thickness MAPK inhibitor and temperature of the SRO film on STO (001) substrate but this structural transition temperature was not associated with the ferromagnetic transition temperature [4]. While many previous studies have focused on (100)c-oriented SRO films, the in-plane magnetization of thin films on top of STO (001) substrates was smaller than out-of-plane magnetization and T c was smaller than that of bulk SRO [5, 6]. The observed small change of ferromagnetic properties in SRO films has been mostly
explained simply in terms of lattice mismatch. A free-standing film made by lifting the film off its growth substrate recovered its bulk T c and bulk saturated magnetic moment [5, 6]. An SRO film having a structure most similar to the bulk SRO was made using a buffer layer and STO (110) substrate, and its magnetic anisotropy was maximum [7–9]. The observed changes in SRO films on STO (110) was explained based on the inherently lower lattice mismatch of the orthorhombic crystal along the cubic substrate’s [1–10] in-plane direction than along the cubic substrate’s [001] in-plane direction 17-DMAG (Alvespimycin) HCl [9]. So, the lattice mismatch of orthorhombic crystal can always be smaller by choosing a cubic (110) substrate instead of a cubic (001) substrate. (In this report, we use pseudocubic notation for SRO films. (110)orthorhombic is equivalent to (100)c in the pseudocubic notation). Up to now, the tolerance factor, t = (r A + r O )/√2(r B + r O ), was widely regarded as the most dominant factor to determine the structural transition from cubic to lower symmetries and accompanying huge changes in magnetic and electrical properties of many perovskite oxides [10–12].