Characterisation of cation order in A-site doped polar hexagonal multiferroic MnAMo 3 O 8 (A 2+ = Fe, Co, Zn) Holly McPhillips 1,2 , Laura J. Vera Stimpson 3 , Pascal Manuel 4 , Gavin B. G. Stenning 4 , Iuliia Mikulska 5 , Donna C. Arnold 1 and Silvia Ramos 2 1 School of Chemistry and Forensic Science, Division of Natural Sciences, University of Kent, Canterbury, UK, CT2 7NH 2 School of Physics and Astronomy, Division of Natural Sciences, University of Kent, Canterbury, UK, CT2 7NH 3 School of Law, Policing and Social Sciences, Canterbury Christ Church University, Canterbury, Kent, UK, CT1 1QU 4 ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, UK, OX11 0QX 5 Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK, OX11 0DE Multiferroic materials that have multiple order parameters co-existing in a single phase have continued to attract great interest in the scientific community. In particular, the magnetoelectric effect, where the electric polarisation and magnetic order parameters are coupled, has applications in data storage and spintronic devices. This is seen for the polar hexagonal multiferroic layered oxide ( S = 5/2) Mn 2 Mo 3 O 8 , which exhibits large ME coupling that would benefit these emerging technological devices. However, understanding the structure-property correlations in this material remains an open question, particularly when the structure is doped with other 3 d transition metals. The structure of Mn 2 Mo 3 O 8 is composed of stacked Mn-O layers separated by trimerised Mo 3 O 13 sheets, crystallising in P 6 3 mc 1,2 . The Mn-O layer is a 1:1 ratio of alternating corner-sharing MnO 4 tetrahedra (Mn1) and MnO 6 octahedra (Mn2), resulting in honeycomb connectivity. Kagomé-like connectivity is seen in the trimerised Mo 4+ sheets due to formation of non-magnetic spin singlet trimers. Therefore, the magnetic behaviour of Mn 2 Mo 3 O 8 is driven by the honeycomb-like layer, resulting in an easy-axis-type ferrimagnetic ground state below T c = 41 K. Doping the honeycomb motif with other 3 d transition metals ( A 2+ = Fe, Co, Zn) considerably alters the observed magnetic behaviour 3,4 . However, understanding how the structure has changed when doped, in terms of site preference and electronic structure, and the resulting magnetic behaviour remains to be fully addressed. This discussion will primarily focus on understanding the local structure and cation order in Mn A Mo 3 O 8 , using two complementary techniques: neutron diffraction and x-ray absorption spectroscopy. From these studies, we can begin to understand the stability of the interactions present within the honeycomb motif, including the possibility of geometric magnetic frustration that may be responsible for the observed magnetic behaviour, and provide an insight into the design and development of new materials that can exhibit desirable properties like the ME effect. References 1. S. P. McAlister, J. Appl. Phys ., 1984, 55 , 2343–2345. 2. D. Szaller, K. Szász, S. Bordács, J. Viirok, T. Rõõm, U. Nagel, A. Shuvaev, L. Weymann, A. Pimenov, A. A. Tsirlin, A. Jesche, L. Prodan, V. Tsurkan and I. Kézsmárki, Phys. Rev. B , 2020, 102 , 1–8. 3. T. Kurumaji, S. Ishiwata and Y. Tokura, Phys. Rev. B , 2017, 95 , 1–9. 4. S. Nakayama, R. Nakamura, M. Akaki, D. Akahoshi and H. Kuwahara, J. Phys. Soc. Japan , 2011, 80 , 1–4.
P96F
Made with FlippingBook Learn more on our blog