Watanabe, T;
Takayanagi, K;
Nishimura, R;
Hara, Y;
Prabhakaran, D;
Johnson, RD;
Blundell, SJ;
(2025)
Elastic softness of low-symmetry frustrated.
Physical Review B
, 111
(2)
, Article 024426. 10.1103/PhysRevB.111.024426.
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Abstract
Orthorhombic pseudobrookites CoTi2O5 and FeTi2O5 have a low-symmetry crystal structure comprising magnetic Co2+/Fe2+ ions and nonmagnetic Ti4+ ions, where the orbital-nondegenerate Co2+/Fe2+ ions form one-dimensional chains running along the orthorhombic a axis. These compounds undergo an antiferromagnetic phase transition at TN∼ 26 K for CoTi2O5 and TN∼ 40 K for FeTi2O5. Ultrasound velocity measurements on single crystals of CoTi2O5 and FeTi2O5 reveal that CoTi2O5 exhibits unusual elastic softness above TN in the symmetry-lowering elastic mode of ac-plane shear elastic modulus, inconsistent with the structural symmetry breaking caused by antiferromagnetic ordering at TN. This suggests the presence of two distinct types of magnetostructural fluctuations above TN that should be a precursor to the symmetry-lowering lattice distortion at TN. In contrast, FeTi2O5 exhibits either negligible or smaller elastic softness, indicating weaker spin-lattice coupling. These findings highlight CoTi2O5 and FeTi2O5 as unique spin-latticed-coupled frustrated systems with low crystal symmetry, where, while the exchange interactions are quasi-one-dimensional in nature, the frustration is released by further lowering the crystal symmetry through three-dimensional spin-lattice coupling, which is stronger in CoTi2O5 than in FeTi2O5.
| Type: | Article |
|---|---|
| Title: | Elastic softness of low-symmetry frustrated |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1103/PhysRevB.111.024426 |
| Publisher version: | https://doi.org/10.1103/physrevb.111.024426 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Technology, Physical Sciences, Materials Science, Multidisciplinary, Physics, Applied, Physics, Condensed Matter, Materials Science, Physics, VALENCE TRANSITION, PHASE-TRANSITION, TELLER |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10205460 |
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