Magnetic and structural correlations in the warwickite Mn2OBO3
V. Gnezdilov1,2, Yu. Pashkevich3, V. Kurnosov1, O.V. Zhuravlev3, D. Wulferding2, P. Lemmens2, N.V. Kazak4, Yu.V. Knyazev4, and S.G. Ovchinnikov4,5
1B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine
47 Nauki Ave., Kharkiv 61103, Ukraine
E-mail: gnezdilov@ilt.kharkov.ua
2Institute for Condensed Matter Physics, TU Braunschweig, Braunschweig D-38106, Germany
3O.O. Galkin Donetsk Institute for Physics and Engineering of the National Academy of Sciences of Ukraine
46 Nauki Ave., Kyiv 03680, Ukraine
4Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Krasnoyarsk 660036, Russia
5School of Engineering Physics and Radio Electronics, Siberian Federal University, Krasnoyarsk 660041, Russia
Received April 16, 2019, published online July 26, 2019
Abstract
We report a Raman scattering study of single-crystalline homometallic oxyborate Mn2OBO3, a compound realizing a one-dimensional ribbon-structure. Phonon excitations as a function of temperature and light polarization are compared to lattice dynamical calculations, giving evidence for a strong coupling between lattice and magnetic degrees of freedom. Furthermore, a broader feature with a distinct structure emerges at low temperatures. Based on our theoretical analysis, we assign this signal to specific two-magnon scattering processes related to high energy flat-band magnon branches.
Key words: geometric frustration, two-magnon Raman scattering, oxyborate.
