Abstract
We report a thorough study of Y0.7La0.3VO3 single crystals by measuring magnetic properties, specific heat, thermal conductivity, Raman scattering, X-ray and neutron diffraction with the motivation of revealing the lattice response to the spin-orbital entanglement in RVO3. Upon cooling from room temperature, the orbitally disordered paramagnetic state changes around T∗∼220 K to a spin-orbital entangled state which is then followed by a transition at TN = 116 K to C-type orbital-ordered (OO) and G-type antiferromagnetic ordered (AF) ground state. In the temperature interval TN<T<T∗, the VO6/2 octahedra have two comparable in-plane V-O bonds which are longer than the out-of-plane V-O1 bond. This octahedral site distortion supports the spin-orbital entanglement of partially filled and degenerate yz/zx orbitals. However, this distortion is incompatible with the steric octahedral site distortion intrinsic to orthorhombic perovskites. Their competition induces a second-order transition from the spin-orbital entangled state to a C-OO/G-AF ground state where the long-range OO suppresses the spin-orbital entanglement. Our analysis suggests that the spin-orbital entangled state and G-OO are comparable in energy and compete with each other. Rare-earth site disorder favors the spin-orbital entanglement rather than a cooperative Jahn-Teller distortion. The results also indicate for LaVO3 a C-OO/G-AF state in Tt ≤ T ≤TN and an orbital flipping transition at Tt.
| Original language | English |
|---|---|
| Article number | 184423 |
| Journal | Physical Review B |
| Volume | 100 |
| Issue number | 18 |
| DOIs | |
| State | Published - Nov 27 2019 |
Funding
The authors thank Dr. S. Chang for his exploratory neutron diffraction work on this compound at the early stage of this project. Work at ORNL and Ames Laboratory was supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Division of Materials Sciences and Engineering. Ames Laboratory is operated for the US Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358. Q.C. acknowledges the support of the Center for Emergent Materials, an NSF MRSEC, under Award No. DMR-1420451. J.G.C. is supported by the MOST, NSFC, and CAS (Grants No. 2018YFA0305700, No. 11574377, No. XDB07020100, and No. QYZDB-SSW-SLH013). J.S.Z. acknowledges support from the Gordon and Betty Moore Foundation EPiQS Initiative through a subcontract to Grant No. GBMF4534. J.M. is supported by the NSFC (Grants No. 11774223 and No. U1732154). A portion of this research used resources at the High Flux Isotope Reactor and Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Raman measurements were conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. Work at Argonne National Laboratory was supported by the US Department of Energy, Division of Basic Energy Science, under Contract No. DE-AC02-CH11357. This work has benefited from the use of HIPD at the Lujan Center at Los Alamos Neutron Science Center, funded by DOE Office of Basic Energy Sciences. Los Alamos National Laboratory is operated by Los Alamos National Security LLC under DOE Contract No. DE-AC52-06NA25396.