On the superparamagnetic size limit of nanoparticles on a ferroelectric substrate

Abstract

Abstract. When decreasing the size of nanoscale magnetic particles their magnetization becomes vulnerable to thermal fluctuations as approaching the superparamgnetic limit, hindering thus applications relying on a stable magnetization. Here, we show theoretically that a magnetoelectric coupling to a ferroelectric substrate renders possible the realization of substantially smaller nano clusters with thermally stable magnetization. For an estimate of cluster size we perform calculations with realistic material parameters for iron nano particles on ferroelectric BaTiO 3 substrate. We find, steering the polarization of BaTiO 3 with electric fields affects the magnetism of the deposited magnetic clusters. These findings point to a qualitatively new class of superparamagnetic composites.

The Influence of Functionalization of the Fe3O4 Nanoparticle on its Dispersion Property

“…In particular, the high saturation magnetization value and coercive force, which are superparamagnetic properties that are expressed when ferromagnetic substances are downsized to nanoparticles, and the absence of a residual magnetization value, 3 )…”

Landau–Zener tunneling in multiferroic composites

“…For insight into the time dynamics of the correlated electric dipoles and magnetic moments in multiferroics [27][28][29] we consider a minimal but relevant ladder model consisting of two weakly coupled chains: the first chain is FE, built by one-dimensional interacting dipoles, and the second chain is FM, consisting of classical threedimensional magnetic moments. In the case of both single [30][31][32] and two-phase [33][34][35][36] multiferroics, both the FE and FM chains are characterized by intrachain nearest neighbor coupling.…”

Creation and amplification of electromagnon solitons by electric field in nanostructured multiferroics

“…For a proper choice of the electric-field frequency (that follows from the electro-magnon soliton theory developed below) it is possible to excite propagating magnetic solitons. In addition, we point out a possibility for the amplification of weak magnetic signals, which suggests the design of a digital magnetic transistor, where the role of the pump is played by the electric field.Examples of the two-phase multiferroics under study [9][10][11][12], are BaTiO 3 /CoFe 2 O 4 or PbZr 1−x Ti x O 3 /ferrites. The developed model will be applied to a system where the FE and FM regions are coupled at an interface whith a weak magnetoelectric coupling.…”

“…Examples of the two-phase multiferroics under study [9][10][11][12], are BaTiO 3 /CoFe 2 O 4 or PbZr 1−x Ti x O 3 /ferrites. The developed model will be applied to a system where the FE and FM regions are coupled at an interface whith a weak magnetoelectric coupling.…”

“…In the weakly nonlinear limit it is even possible to construct a solution for the case when particular modes overlap (i.e., the magnetic soliton is located near the edge), adding a timedependent phase to each term (5) and (8) in the sum [26]. For instance, one can consider an approximate solution at the left edge of the ladder, n = 0, in the form of (12) where, in the weakly-nonlinear limit, the phases Ψ are proportional to the wave amplitudes. Hence the waves do not gain significant phase shifts due to interaction effects, if their relative group velocity is not negligible.…”