Abstract
Calcium vanadate CaV2O4 has a crystal structure of quasi-one-dimensional zigzag chains composed of orbital-active V3+ ions and undergoes successive structural and antiferromagnetic phase transitions at Ts∼140 K and TN∼70 K, respectively. We perform ultrasound velocity measurements on a single crystal of CaV2O4. The temperature dependence of its shear elastic moduli exhibits huge Curie-type softening upon cooling that emerges above and below Ts depending on the elastic mode. The softening above Ts suggests the presence of either onsite Jahn-Teller-type or intersite ferrotype orbital fluctuations in the two inequivalent V3+ zigzag chains. The softening below Ts suggests the occurrence of a dimensional spin-state crossover, from quasi-one to three, that is driven by the spin-lattice coupling along the inter-zigzag-chain orthogonal direction. The successive emergence of the orbital- and spin-driven lattice instabilities above and below Ts, respectively, is unique to the orbital-spin zigzag chain system of CaV2O4.
| Original language | English |
|---|---|
| Article number | 094427 |
| Journal | Physical Review B |
| Volume | 98 |
| Issue number | 9 |
| DOIs | |
| State | Published - Sep 26 2018 |
Funding
This work was partly supported by Grant-in-Aid for Scientific Research (C) (Grant No. 17K05520) from MEXT of Japan, and by Nihon University College of Science and Technology Grant-in-Aid for Research. The research at Ames Laboratory was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering. Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358. This work was partly supported by Grant-in-Aid for Scientific Research (C) (Grant No. 17K05520) from MEXT of Japan, and by Nihon University College of Science and Technology Grant-in-Aid for Research. The research at Ames Laboratory was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering. Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358.