Qingshan Lu

Magneto-dielectric and magnetoelectric anisotropies of CoFe2O4/Bi5Ti3FeO15 bilayer composite heterostructural films

Bilayer composite heterostructural films consisting of magnetic CoFe2O4 and multiferroic Bi5Ti3FeO15 films were prepared by the chemical solution deposition method. Morphological, ferroelectric, piezoelectric, magnetic, magneto-dielectric and magnetoelectric properties were investigated for CoFe2O4/Bi5Ti3FeO15 composite films. The magneto-dielectric and magnetoelectric effects are observed for the composite films, which is attributed to the enhanced interface coupling and mechanical strain transfer due to the small lattice mismatch between CoFe2O4 and Bi5Ti3FeO15 film layers. Magneto-dielectric and magnetoelectric anisotropies were also observed for the composite films. Correspondingly, the in-plane and out-of-plane magnetoelectric voltage coefficients reach 57 mV cm−1 Oe−1 and 78.9 mV cm−1 Oe−1, respectively. Thus magneto-dielectric and magnetoelectric anisotropies originate from the magnetic anisotropy of CoFe2O4/Bi5Ti3FeO15 composite films. The present work provides promising candidates for applications in magnetoelectric devices.

Enhanced magnetostriction derived from magnetic single domain structures in cluster-assembled SmCo films

Cluster-assembled SmCo alloy films were prepared by low energy cluster beam deposition. The structure, magnetic domain, magnetization, and magnetostriction of the films were characterized. It is shown that the as-prepared films are assembled in compact and uniformly distributed spherical cluster nanoparticles, most of which, after vacuum in situ annealing at 700 K, aggregated to form cluster islands. These cluster islands result in transformations from superparamagnetic states to magnetic single domain (MSD) states in the films. Such MSD structures contribute to the enhanced magnetostrictive behaviors with a saturation magnetostrictive coefficient of 160xa0×xa010-6 in comparison to 105xa0×xa010-6 for the as-prepared films. This work demonstrates candidate materials that could be applied in nano-electro-mechanical systems, low power information storage, and weak magnetic detecting devices.