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

Abstract

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.