Orthorhombic distortion drives orbital ordering in an antiferromagnetic 3$d^1$ Mott insulator

Abstract

The orbital, which represents the shape of the electron cloud, very often strongly influences the manifestation of various exotic phenomena, e.g., magnetism, metal-insulator transition, colossal magnetoresistance, unconventional superconductivity etc. in solid-state systems. The observation of the antiferromagnetism in $RE$TiO${}_3$ ($RE$=rare earth) series has been puzzling since the celebrated Kugel-Khomskii model of spin-orbital super exchange predicts ferromagnetism in an orbitally degenerate $d^1$ systems. Further, the existence of the orbitally ordered vs. orbital liquid phase in both antiferromagnetic and paramagnetic phase have been unsettled issues thus far. To address these long-standing questions, we investigate single crystalline film of PrTiO${}_3$. Our synchrotron X-ray diffraction measurements confirm the retention of bulk-like orthorhombic ($D_{2h}$) symmetry in the thin film geometry. We observe similar X-ray linear dichroism signal in both paramagnetic and antiferromagnetic phase, which can be accounted by ferro orbital ordering (FOO). While the presence of $D_{2h}$ crystal field does not guarantee lifting of orbital degeneracy always, we find it to be strong enough in these rare-earth titanates, leading to the FOO state. Thus, our work demonstrates the orthorhombic distortion is the driving force for the orbital ordering of antiferromagnetic $RE$TiO${}_3$.

37 pages and 17 figures

References in corpus (8)

• Orbital Physics in the Perovskite Ti Oxides
• Magnetoelastic coupling in RETiO3 (RE = La, Nd, Sm, Gd, Y)
• Orbital-Spin Structure and Coupling to Lattice in RTiO${}_3$ with R=La,Pr,Nd and Sm
• Determination of the orbital moment and crystal field splitting in LaTiO${}_3$
• Lattice Distortion and Magnetic Ground State of YTiO${}_3$ and LaTiO${}_3$
• Anomalous orbital structure in a spinel-perovskite interface $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$
• Origin of the orbital and spin orderings in rare-earth titanates
• Giant orbital polarization of Ni${}^{2+}$ in square planar environment

Cited by in corpus (2)

• Embracing Disorder in Quantum Materials Design
• Interfacial reconstruction effects in insulating double perovskite Nd${}_2$NiMnO${}_6$/SrTiO${}_3$ and Nd${}_2$NiMnO${}_6$/NdGaO${}_3$ thin films