Low Temperature Physics: 43, 543 (2017); https://doi.org/10.1063/1.4985205
Fizika Nizkikh Temperatur: Volume 43, Number 5 (May 2017), p. 683-691    ( to contents , go back )

Comparative Raman scattering study of Ba3MSb2O9 (M=Zn, Co and Cu)

A. Glamazda1,2, P. Lemmens3,S.-H. Do1, and K.-Y. Choi1

1Department of Physics, Chung-Ang University, Seoul 156-756, Republic of Korea
E-mail: kchoi@cau.ac.kr

2B. Verkin Institute for Low Temperature Physics and Engeneering of the National Academy of Sciences of Ukraine 47 Nauky Ave, Kharkiv 61103, Ukraine

3Institute for Condensed Matter Physics, TU Braunschweig, Braunschweig D-38106, Germany

Received October 11, 2016

Abstract

Raman spectroscopy is combined with lattice dynamic calculations to investigate the magnetic and structural properties of the 6H-perovskite compounds Ba3MSb2O9 (M = Zn, Co and Cu). Unlike the nonmagnetic Ba3ZnSb2O9 compound, the magnetic counterparts Ba3MSb2O9 (M = Co and Cu) show both lattice anomalies for temperatures below 100 K and develop highly correlated spin states below 50 K. This is ascribed to an instability of сonventional magnetic excitations for the equilateral triangular antiferromagnet Ba3CoSb2O9 and a co-existence of spin-orbital liquid and random singlet state for the decorated honeycomb compound Ba3CuSb2O9 containing a nearly identical volume fraction of hexagonal and orthorhombic phases. Our results demonstrate that Ba3MSb2O9 provides a rich reservoir for hosting diverse magnetic and structural phases as a function of the metal ion M.

PACS: 63.20.–e Phonons in crystal lattices;
PACS: 75.45.+j Macroscopic quantum phenomena in magnetic systems;
PACS: 78.30.–j Infrared and Raman spectra.

Key words: spin frustration, spin-phonon coupling, Raman scattering.

Published online: March 24, 2017

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