Magnetic ordering and structural phase transitions in strained ultrathin SrRuO\(_{3}\)/SrTiO\(_{3}\) superlattice

• Published in: arXiv.org
• Main Authors: Gu, Mingqiang, Xie, Qiyun, Shen, Xuan, Rubin, Xie, Wang, Jianli, Tang, Gang, Wu, Di, Zhang, G P, Wu, X S
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 29.08.2012
• Subjects: Antiferromagnetism; Ferromagnetism; First principles; Magnetic properties; Orbitals; Perovskites; Phase transitions; Physics - Strongly Correlated Electrons; Ruthenium; Superlattices; Tensile strain; Tensors; Unit cell
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1208.5945

Ruthenium-based perovskite systems are attractive because their Structural, electronic and magnetic properties can be systematically engineered. SrRuO\(_3\)/SrTiO\(_3\) superlattice, with its period consisting of one unit cell each, is very sensitive to strain change. Our first-principles simulations reveal that in the high tensile strain region, it transits from a ferromagnetic (FM) metal to an antiferromagnetic (AFM) insulator with clear tilted octahedra, while in the low strain region, it is a ferromagnetic metal without octahedra tilting. Detailed analyses of three spin-down Ru-t\(_{2g}\) orbitals just below the Fermi level reveal that the splitting of these orbitals underlies these dramatic phase transitions, with the rotational force constant of RuO\(_6\) octahedron high up to 16 meV/Deg\(^2\), 4 times larger than that of TiO\(_6\). Differently from nearly all the previous studies, these transitions can be probed optically through the diagonal and off-diagonal dielectric tensor elements. For one percent change in strain, our experimental spin moment change is -0.14\(\pm\)0.06 \(\mu_B\), quantitatively consistent with our theoretical value of -0.1 \(\mu_B\).