Fe-induced enhancement of antiferromagnetic spin correlations in Mn2-xFexBO4

Kazak, NV; Platunov, MS; Knyazev, YV; Moshkina, EM; Gavrilkin, SY; Bayukov, OA; Gorev, MV; Pogoreltsev, EI; Zeer, GM; Zharkov, SM; Ovchinnikov, SG JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 452 90-99; 10.1016/j.jmmm.2017.12.037 APR 15 2018

Fe substitution effect on the magnetic behavior of Mn2−xFexBO4 (x = 0.3, 0.5, 0.7) warwickites has been investigated combining Mössbauer spectroscopy, dc magnetization, ac magnetic susceptibility, and heat capacity measurements. The Fe3+ ions distribution over two crystallographic nonequivalent sites is studied. The Fe introduction breaks a long-range antiferromagnetic order and leads to onset of spin-glass ground state. The antiferromagnetic short-range-order spin correlations persist up to temperatures well above TSG reflecting in increasing deviations from the Curie-Weiss law, the reduced effective magnetic moment and “missing” entropy. The results are interpreted in the terms of the progressive increase of the frustration effect and the formation of spin-correlated regions.