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Orbital-and spin-driven lattice instabilities in quasi-one-dimensional CaV2O4

TitleOrbital-and spin-driven lattice instabilities in quasi-one-dimensional CaV2O4
Publication TypeJournal Article
Year of Publication2018
AuthorsWatanabe, T, Kobayashi, S, Hara, Y, Xu, J, Lake, B, Yan, JQ, Niazi, A, Johnston, DC
JournalPhysical Review B
Date Published09
Type of ArticleArticle
ISBN Number2469-9950
Accession NumberWOS:000445724200004
Keywordsphysics, vanadite

Calcium vanadate CaV2O4 has a crystal structure of quasi-one-dimensional zigzag chains composed of orbitalactive V3+ ions and undergoes successive structural and antiferromagnetic phase transitions at Ts similar to 140 K and TN similar to 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.

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Alternate JournalPhys. Rev. B