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Electric-field control of perpendicular magnetic anisotropy (PMA) is a feasible way to manipulate perpendicular magnetization, which is of great importance for realizing energy-efficient spintronics. Here, we propose a novel approach to accomplish this task at room temperature by resistive switching (RS) via electrochemical metallization (ECM) in a device with the stack of Si/SiO2/Ta/Pt/Ag/Mn-doped ZnO (MZO)/Pt/Co/Pt/ITO. By applying certain voltages, the device could be set at high-resistance-state (HRS) and low-resistance-state (LRS), accompanied with a larger and a smaller coercivity (H C), respectively, which demonstrates a nonvolatile E-field control of PMA. Based on our previous studies and the present control experiments, the electric modulation of PMA can be briefly explained as follows. At LRS, the Ag conductive filaments form and pass through the entire MZO layer and finally reach the Pt/Co/Pt sandwich, leading to weakening of PMA and reduction of H C. In contrast, at HRS, most of the Ag filaments dissolve and leave away from the Pt/Co/Pt sandwich, causing partial recovery of PMA and an increase of H C. This work provides a new clue to designing low-power spintronic devices based on PMA films.

The realization of perpendicular magnetization and perpendicular exchange bias (PEB) in magnetic multilayers is important for the spintronic applications. NiO(t)/[Ni(4 nm)/Pt(1 nm)]2 multilayers with varying the NiO layer thickness t have been epitaxially deposited on SrTiO3 (001) substrates. Perpendicular magnetization can be achieved when t < 25 nm. Perpendicular magnetization originates from strong perpendicular magnetic anisotropy (PMA), mainly resulting from interfacial strain induced by the lattice mismatch between the Ni and Pt layers. The PMA energy constant decreases monotonically with increasing t, due to the weakening of Ni (001) orientation and a little degradation of the Ni–Pt interface. Furthermore, significant PEB can be observed though NiO layer has spin compensated (001) crystalline plane. The PEB field increases monotonically with increasing t, which is considered to result from the thickness dependent anisotropy of the NiO layer.

Tuning magnetic damping constant in dedicated spintronic devices has important scientific and technological implications. Here we report on anisotropic damping in various compositional amorphous CoFeB films grown on GaAs(001) substrates. Measured by a vector network analyzer-ferromagnetic resonance (VNA-FMR) equipment, a giant magnetic damping anisotropy of 385%, i.e., the damping constant increases by about four times, is observed in a 10-nm-thick Co40Fe40B20 film when its magnetization rotates from easy axis to hard axis, accompanied by a large and pure in-plane uniaxial magnetic anisotropy (UMA) with its anisotropic field of about 450 Oe. The distinct damping anisotropy is mainly resulted from anisotropic two-magnon-scattering induced by the interface between the ferromagnetic layer and the substrate, which also generates a significant UMA in the film plane.

The FeCo/AlOx/Co magnetic tunnel junction was fabricated using a two-step plasma oxidation technique. The tunnelling magneto-resistance ratio of the junction as-deposited was about 8.5%, and reached 14.0% after annealing at 200°C. Transmission electron microscopy, high-resolution electron microscopy and electron holography were used to study the microstructure of the junction. The enhancement of the magneto-resistance effect after annealing could be attributed to the uniformity of the barrier layer, the improvement of FM/I interfaces, and the deoxidization of the bottom ferromagnetic electrode.

A general model of a hybrid interfacial domain wall (HIDW) in ferromagnetic/antiferromagnetic exchange biased bilayers is proposed, where an interfacial domain wall is allowed to extend into either the ferromagnetic or antiferromagnetic layer or across both. The proposition is based on our theoretical investigation on thickness and field dependences of ferromagnetic domain wall (FMDW) and antiferromagnetic domain wall (AFDW), respectively. Good match of the simulation to the hysteresis loops of a series of NiFe/FeMn exchange-biased bilayers confirms the existence of the HIDW, where the AFDW part is found to preferentially occupy the entire antiferromagnetic layer while the FMDW shrinks with the increased magnetic field as expected. The observed asymmetry between the ascending and descending branches of the hysteresis loop is explained naturally as a consequence of different partition ratios between AFDW and FMDW.