Spin Jahn-Teller antiferromagnetism in CoTi2O5

Kirschner, Franziska K.K.; Johnson, Roger D.; Lang, Franz; Khalyavin, Dmitry D.; Manuel, Pascal; Lancaster, Tom; Prabhakaran, Dharmalingam; Blundell, Stephen J.

Abstract

We have used neutron powder diffraction to solve the magnetic structure of orthorhombic CoTi2O5, showing that the long-range ordered state below 26 K identified in our muon-spin rotation experiments is antiferromagnetic with propagation vector k = (±1 2 , 1 2 , 0) and moment of 2.72(1)μB per Co2+ ion. This long-range magnetic order is incompatible with the experimentally determined crystal structure because the imposed symmetry completely frustrates the exchange coupling. We conclude that the magnetic transition must therefore be accompanied by a spin Jahn-Teller effect which lowers the structural symmetry and thereby relieves the frustration. These results show that CoTi2O5 is a highly unusual low-symmetry material exhibiting a purely spin-driven lattice distortion critical to the establishment of an ordered magnetic ground state.

Citation

Kirschner, F. K., Johnson, R. D., Lang, F., Khalyavin, D. D., Manuel, P., Lancaster, T., Prabhakaran, D., & Blundell, S. J. (2019). Spin Jahn-Teller antiferromagnetism in CoTi2O5. Physical Review B, 99(6), Article 064403. https://doi.org/10.1103/physrevb.99.064403

• Journal Article Type: Article
• Acceptance Date: Jan 22, 2019
• Online Publication Date: Feb 4, 2019
• Publication Date: Feb 4, 2019
• Deposit Date: Feb 5, 2019
• Publicly Available Date: Feb 7, 2019
• Journal: Physical Review B
• Print ISSN: 2469-9950
• Electronic ISSN: 2469-9969
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 99
• Issue: 6
• Article Number: 064403
• DOI: https://doi.org/10.1103/physrevb.99.064403
• Public URL: https://durham-repository.worktribe.com/output/1308692
• Related Public URLs: https://arxiv.org/abs/1808.01387