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Understanding the high-frequency transport characteristics of magnetic tunnel junctions (MTJs) is crucial for the development of fast-operating spintronics memories and radio frequency devices. Here, we present the study of frequency-dependent capacitive current effect in CoFeB/MgO-based MTJs and its influence on magnetization dynamics using time-resolved magneto-optical Kerr effect technique. In our device operating at gigahertz frequencies, we find a large displacement current of the order of mA's, which does not break the tunnel barrier of the MTJ. Importantly, this current generates an Oersted field and spin-orbit torque, inducing magnetization dynamics. Our discovery holds promise for building robust MTJ devices operating under high current conditions, also highlighting the significance of capacitive impedance in high frequency magnetotransport techniques.

Artificial multiferroics consist of two types of ferroic materials, typically a ferroelectric and ferromagnet, often coupled interfacially by magnetostriction induced by the lattice elongations in the ferroelectric. In BaTiO3 the magnitude of strain induced by these elongations is heavily temperature dependent, varying greatly between each of the polar crystal phases and exerting a huge influence over the properties of a coupled magnetic film. Here we demonstrate that temperature, and thus strain, is an effective means of controlling the magnetic anisotropy in BaTiO3(111)/CoFeB heterostructures. We investigate the three polar phases of BaTiO3: tetragonal (T) at room temperature, orthorhombic (O) below 280 K and rhombohedral (R) below 190 K, across a total range of 77 K to 420 K. We find two distinct responses; a step-like change in the anisotropy across the low-temperature phase transitions, and a sharp high-temperature reduction around the ferroelectric Curie temperature, measured from hard axis hysteresis loops. Using our measurements of this anisotropy strength we are then able to show by micromagnetic simulation the behaviour of all possible magnetic domain wall states and determine their scaling as a function of temperature. The most significant changes occur in the head-to-head domain wall states, with a maximum change of 210 nm predicted across the entire range effectively doubling the size of the domain wall as compared to room temperature. Notably, similar changes are seen for both high and low temperatures which suggest different routes for potential control of magnetic anisotropy and elastically pinned magnetic domain walls., Comment: 7 pages, 7 figures. Supplementary information contains 2 figures

Two-dimensional (2D) van der Waals (vdW) magnets represent one of the most promising horizons for energy-efficient spintronic applications because their broad range of electronic, magnetic and topological properties. Of particular interest is the control of the magnetic properties of 2D materials by femtosecond laser pulses which can provide a real path for low-power consumption device platforms in data storage industries. However, little is known about the interplay between light and spin properties in vdW layers. Here, combining large-scale spin dynamics simulations including biquadratic exchange interactions and wide-field Kerr microscopy (WFKM), we show that ultrafast laser excitation can not only generate different type of spin textures in CrGeTe$_3$ vdW magnets but also induce a reversible transformation between them in a toggle-switch mechanism. Our calculations show that skyrmions, anti-skyrmions, skyrmioniums and stripe domains can be generated via high-intense laser pulses within the picosecond regime. The effect is tunable with the laser energy where different spin behaviours can be selected, such as fast demagnetisation process ($\sim$250 fs) important for information technologies. The phase transformation between the different topological spin textures is obtained as additional laser pulses are applied to the system where the polarisation and final state of the spins can be controlled by external magnetic fields. We experimentally confirmed the creation, manipulation and toggle switching phenomena in CrGeTe$_3$ due to the unique aspect of laser-induced heating of electrons. Our results indicate laser-driven spin textures on 2D magnets as a pathway towards ultrafast reconfigurable architecture at the atomistic level.