Giant magnetoelastic effects in BaTiO3-based extrinsic multiferroic hybrids

Abstract

Extrinsic multiferroic hybrid structures consisting of ferromagnetic and ferroelectric layers elastically coupled to each other are promising due to their robust magnetoelectric effects even at room temperature. For a quantitative analysis of these magnetoelectric effects, a detailed knowledge of the piezoelectric and magnetoelastic behavior of both constituents as well as their mutual elastic coupling is mandatory. We here report on a theoretical and experimental study of the magnetic behavior of BaTiO3-based extrinsic multiferroic structures. An excellent agreement between molecular dynamics simulations and the experiments was found for Fe50Co50/BaTiO3 and Ni/BaTiO3 hybrid structures. This demonstrates that the magnetic behavior of extrinsic multiferroic hybrid structures can be determined by means of ab-initio calculations, allowing for the design of novel multiferroic hybrids.

Strain induced changes in magnetization of amorphous Co95Zr5 based multiferroic heterostructures

“…22 The anisotropic strain is mediated via the non-magnetic Al 70 Zr 30 buffer layer into the bulk of the amorphous ferromagnetic CoZr film at the orthorhombic phase transition of BaTiO 3 thereby causing the enhancement of the uniaxial magnetic anisotropy. A similar conclusion is drawn by Geprägs et al 23 from detailed measurements on crystalline thin ferromagnetic films on single crystalline BaTiO 3 substrates, with controlled ferroelectric domain structure. The strain induced magnetic anisotropy governs the variation of the measured magnetization with temperature, at weak magnetic fields.…”

Converse magnetoelectric effects in Fe3O4/BaTiO3multiferroic hybrids

“…63 We demonstrated that the manipulation of the magnetization in BTO-based multiferroic hybrid structures can be theoretically well described by controlling the ferromagnetic and ferroelastic domain configuration in the multiferroic hybrid. Here, as a second step, we show that by knowing the ferroelastic domain configuration in the BTO substrate as a function of the applied electric field, the strain-mediated converse magnetoelectric effect in epitaxially grown …”

“…Even a strain-induced transition from a magnetically ordered/electrically conducting to a nonmagnetic/insulating state is possible by changing the spin state of the magnetic ions. 83 Since previous experiments showed that changes of the magnetic anisotropy are the driving force behind the converse magnetoelectric effects in Fe 3 O 4 /BTO hybrids, 63 we neglect any strain-induced modification of the saturation magnetization M s and assume M s to be homogeneous throughout the Fe 3 O 4 thin film. In this approximation, the magnetization values M c and M a are described by M c = M s m c and M a = M s m a , respectively.…”

Controllable magnetization and resistivity jumps of manganite thin films on BaTiO3 substrate

“…The global transport and magnetic behavior in particular the direction of the jumps should thus reflect the majority part of the films. Other structural factors such as grain boundary and domain wall may affect local properties 36 and play a role in the amplitude of the jumps 16 (shown in the Fig. 3(a), Fig.…”

“…[5][6][7][8][9] In particular, ferroelectric substrate such as BaTiO 3 (BTO) offers additional tunability of strain since the lattice structure of BTO can be influenced by electric field. [10][11][12][13] In bulk, on cooling the structure of BTO changes from cubic to tetragonal at ferroelectric Tc of ∼ 400 K, and from tetragonal to monoclinic at 268 K, and from monoclinic (M) to rhombohedral (R) at 183 K. 14,15 Even without applying electric field, it has been shown that the structural transitions of the BTO induces distinct jumps of magnetization of 3d metals, [16][17][18][19][20][21] [29][30][31][32][33] films grown epitaxially on BTO substrates. The magnetization jump becomes especially interesting for the La 1−x Sr x MnO 3 (LSMO) and La 1−x Ca x MnO 3 (LCMO) thin films grown on BTO substrate since it gives rise to a giant and reversible magnetocaloric effect.…”