Magnetic and magnetoelectric properties of some collinear and non-collinear spin ordered magnetic oxides

Abstract

In general, the magnetization of a solid is governed by the spins of the electrons, while the charges of electrons or ions are responsible for electric polarization and thus they can be controlled by applying external magnetic and electric fields, respectively. Magnetoelectrics are one of the interesting classes of materials, where magnetization can be induced by applying electric field and electric polarization can be induced by applying magnetic field [1,2]. Therefore, these materials offer a great platform for electric field controlled magnetism and vice versa. The work on magnetoelectric effect started more than a century ago and it has progressed through the pioneering works of many great scientists (Figure 1.1) [1,3,4]. In 1894, Pierre Curie first proposed magnetoelectric effect on the basis of symmetry [5]. Later, Piccardo, Debye and Van Vleck suggested that magnetoelectric effect is impossible [6,7]. After two decades, Landau and Lifshitz showed that magnetoelectric effect may appear in the materials with certain types of magnetic and crystal symmetry [8]. Dzyaloshinskii in 1959 predicted that the antiferromagnetic structure of Cr2O3 should allow linear magnetoelectric effect [9]. This prediction was confirmed by experiments by two different groups. Astrov discovered electric field induced magnetization below magnetic ordering temperature in Cr2O3 [10,11]. Rado and Folen demonstrated the reverse effect i.e., the magnetic field induced electric polarization in Cr2O3 [12]. However, the magnetoelectric coefficient of Cr2O3 is small for application. Thus, many theoretical and experimental investigations were started in search for room temperature magnetoelectric materials with higher magnetoelectric coupling.