Ba8MnNb6O24: A model two-dimensional spin-5/2 triangular lattice antiferromagnet

Rawl, R.; Ge, L.; Lu, Z.; Evenson, Z.; Dela Cruz, C. R.; Huang, Q.; Lee, M.; Choi, E. S.; Mourigal, M.; Zhou, H. D.; Ma, J.

Abstract

We successfully synthesized and characterized the triangular lattice antiferromagnet Ba8MnNb6O24, which comprises equilateral spin-5/2Mn2+ triangular layers separated by six nonmagnetic Nb5+ layers. The detailed susceptibility, specific heat, elastic and inelastic neutron scattering measurements, and spin-wave theory simulation on this system reveal that it has a 120∘ ordering ground state below TN=1.45K with in-plane nearest-neighbor exchange interaction ≈0.11meV. While the large separation 18.9 Å between magnetic layers makes the interlayer exchange interaction virtually zero, our results suggest that a weak easy-plane anisotropy is the driving force for the km=(1/3,1/3,0) magnetic ordering. The magnetic properties of Ba8MnNb6O24, along with its classical excitation spectra, contrast with the related triple perovskite Ba3MnNb2O9, which shows easy-axis anisotropy, and the isostructural compound Ba8CoNb6O24, in which the effective spin-1/2Co2+ spins do not order down to 60 mK and in which the spin dynamics shows signs of strong quantum effects.

Citation

Rawl, R., Ge, L., Lu, Z., Evenson, Z., Dela Cruz, C. R., Huang, Q., Lee, M., Choi, E. S., Mourigal, M., Zhou, H. D., & Ma, J. (2019). Ba8MnNb6O24: A model two-dimensional spin-5/2 triangular lattice antiferromagnet. Physical Review Materials, 3(5), https://doi.org/10.1103/physrevmaterials.3.054412

• Journal Article Type: Article
• Acceptance Date: Mar 28, 2019
• Online Publication Date: May 28, 2019
• Publication Date: 2019-05
• Deposit Date: Oct 23, 2021
• Journal: Physical Review Materials
• Print ISSN: 2475-9953
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 3
• Issue: 5
• DOI: https://doi.org/10.1103/physrevmaterials.3.054412
• Public URL: http://researchrepository.napier.ac.uk/Output/2815864