Manipulation Of Magnetic Anisotropy Research Articles

Manipulation of magnetic anisotropy by voltage induced strain in Co2MnAl/PMN-PT heterostructure

We have investigated the effect of an external electric field on the magnetic properties of Co2MnAl thin films deposited on a lead magnesium niobate-lead titanate (PMN-PT) (011) substrate. Stain-induced magnetoelectric coupling affects the magnetic properties of the Co2MnAl/PMN-PT system. The piezo-strain induced by applying an external field normal to the surface induces only in-plane strain, which leads to the rotation of easy-axis orientation of Co2MnAl from [100] to [011¯] direction. The remanent magnetization states and coercivity of the Co2MnAl film vary significantly and asymmetrically with the applied voltage due to anisotropic strain originating from PMN-PT. Electrical control of magnetic anisotropy in a Co2MnAl Heusler compound at room temperature will be of interest for realizing next-generation magnetoelectric random access memory devices.

Manipulated magnetic coercivity and spin reorientation transition in NiCo2O4 films

Half-metallic NiCo2O4 with high spin polarizability has great potential applications in spintronics. The manipulation of magnetic anisotropy is crucial for spintronics based on spin-transfer or spin–orbit torques, as it is directly related to the critical switching current density. Here, we report epitaxial growth of metallic NiCo2O4 film with perpendicular magnetic anisotropy on MgAl2O4 single crystal substrates. The modulation of the magnetic anisotropy was achieved by changing the growth conditions (deposition temperature and thickness) of NiCo2O4 films and by means of protonation. Strong dependence of magnetic coercivity on deposition temperature (350–500 °C) has been observed due to variable phase configuration. Furthermore, the magnetic coercive field can also be effectively controlled by the film thickness (3–78 nm) through strain relaxation. More importantly, spin reorientation transition has been achieved by proton and electron doping in the NiCo2O4 films, resulting in reconfigured valence states of Ni and Co cations and a magnetic easy axis rotation from out-of-plane to in-plane. The effective modulation of the magnetic anisotropy provides important insights into the functional design of NiCo2O4-based spintronics with ultralow energy dissipation.

Extraction of the chemical contribution to the interfacial magnetic anisotropy in Ni/Cu3Au(001)

The manipulation of magnetic anisotropy via interface is crucial for spintronics, but its mechanism is still controversial due to the parasitic problem of strain and the chemistry environment. We have independently controlled the interfacial chemistry of the epitaxially grown Ni film on ${\mathrm{Cu}}_{3}\mathrm{Au}(001)$ by inserting the thickness wedged Cu layer. The Ni layer is confirmed to be fully strained until 8 ML by the analysis of LEED I-V spectra, which guarantees that the strain contributions to the magnetic anisotropies are identical. Our results clearly show that the chemistry contribution of Au atoms at $\mathrm{Ni}/{\mathrm{Cu}}_{3}\mathrm{Au}$ interface plays a major role for its perpendicular magnetic anisotropy. We provide a method to quantitatively separate and extract the chemistry and strain contributions to the interfacial magnetic anisotropy, which is helpful for clarifying its mechanism and developing high performance spintronic materials and devices.

Manipulation of magnetic anisotropy in [formula omitted] clusters by Co atom

Based on the first principles calculations, we have investigated the magnetic properties of Irn+1 clusters modulated by Co atoms. The research conclusions show that the amplitude of magnetic anisotropy energy (MAE) and magnetization direction of the small Irn+1 can be manipulated by Co atom if we can control the size very precisely. Such regulatory mechanism of MAE is ascribed to the distributing variation of Ir-5d orbits around the Fermi level induced by Co atom. More importantly, the colossal MAE values, 67.4 meV/atom, 40.26 meV/atom and 91.37 meV/atom, can be obtained for Ir2, Ir4, and CoIr clusters, respectively. Such high values provide a promising avenue for developing high-density magnetic storage units at sub-nanometer size.

Control of magnetic anisotropy by ion-beam-mixing method under external magnetic field

Manipulation of magnetic anisotropy in ferromagnetic thin films was tried with ion-beam-mixing technique. Co/Pt multilayered films were deposited on Si(100) by electron beam evaporation and mixed with an energetic Ar+ ion-beam under external magnetic field which was parallel to the sample surface. The magnetic easy axis was observed from the ion-beam-mixed samples along the direction of applied external magnetic field. When the ion dose was less than a critical dose, a small peak was measured along the magnetic hard axis. The small peak disappeared after ion-beam-mixing with a dose higher than the critical one. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Engineering of a magnetic anisotropy using particles embedded in nano-multilayer structures

We report the manipulation of magnetic anisotropy in a Co/Pt nano-multilayer (nano-ML) system with particles being embedded. The samples, fabricated by a newly-developed normal incidence pulsed laser deposition (NIPLD) method have salient magnetic characteristics, different from particle-free samples of almost the same structure: (1) they exhibit biaxial magnetic anisotropies and (2) there exists a critical field at which the change in easy direction from a parallel direction to a perpendicular direction and vice versa. By the careful manipulation of particles and nano-layers, we also demonstrate the control of the degree of magnetic anisotropy by embedding particles in a well-defined nano-ML system: uniaxial anisotropy to biaxial one and vice versa. This work, indeed, clearly shows that the integration of nano-building blocks into nano-structures can tailor properties of nano-materials.