Magnetic, dielectric and structural properties of nanocrystalline Lu < inf > 1−x < /inf > Ho < inf > x < /inf > FeO < inf > 3 < /inf > orthoferrite solid solutions

Abstract

This work reports on the magnetic, dielectric and structural properties of the nanocrystalline Lu1-xHoxFeO3 (x = 0.0 – 1.0) solid solutions. Ho substitution at the Lu site increases the ground state magnetic moment from 0.245(1) μB per f.u. at x = 0.0 to 4.7 μB per f.u. at x = 1.0. The spin reorientation temperature, TSR, and compensation temperarure, Tcomp, increase with x as ~x2 whereas the Néel temperature, TN, increases as ~x0.4. The variations with x of the ‘field-cooled’ (FC) magnetization, MFC(T=3K,H=100Oe) and the magnetocrystalline anisotropy constant, K1(T=3K), assert that the percolation of the Ho3+ moments and single-ion magnetic anisotropy on the Ho3+ sub-lattices occurs above the threshold concentration of xc≈0.05, which is the minimum Ho concentration for the stabilization of orthorhombic structure in the nanocrystalline Lu1-xHoxFeO3 orthoferrites. A striking similarity between the functional dependences on x of the coercive field, HC, and the magnetocrystalline anisotropy field, HK=2K1/Msat (Msat is the satutation magnetization), indicates that the magnetocrystalline anisotropy on the Ho3+ sub-lattices essentially governs HC(x) at 3 K. Several experimental observations, that firmly support type II multiferroicity in nanocrystalline Lu1-xHoxFeO3, are presented.