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Unidirectional magnetic anisotropy induced by exchange bias (EB) between ferromagnetic and antiferromagnetic layers is of paramount importance in various spintronic devices. Traditional setting and optimization of EB involve cooling through the Néel temperature of the antiferromagnets under biasing field in vacuum furnace which takes hours of time and cannot realize localized control of EB. Herein, an alternative process to configure EB by injection of microsecond current impulse for locally heating of the heterostructure is reported. 180‐degree exchange bias switching has been realized in both anisotropic magnetoresistance and giant magnetoresistance units, resulting in tunable magnetic field sensing functionalities. This mechanism for pinpoint control of EB provides more freedom for the design and optimization of various sensing and logic spintronics. [ABSTRACT FROM AUTHOR]

A strong perpendicular magnetic anisotropy (PMA) and a high thermal stability are essential for long‐term stable storage of data in PMA‐based magnetic tunnel junctions (p‐MTJs). This work investigates the magnetic anisotropy of the MgO/CoFeB/X/CoFeB/MgO double‐interface free layer stacks, where X represents the spacer material. After annealing at 350 °C for an hour, interfacial magnetic anisotropy (Ki) as high as 4.06 mJ m−2 is obtained in the MgO/CoFeB/Mo (0.4 nm)/CoFeB/MgO stacks, much higher than those for Ta‐ and W‐based films. Experimental and first‐principle calculation results demonstrate that bulk PMA plays a great role in the Mo‐based structure, which is often negligible in Ta‐ and W‐based structures. Moreover, a strong PMA is achieved after annealing at 500 °C, which is attributed to the weak interdiffusion and good uniformity as shown in high‐resolution transmission electron microscopy and energy‐dispersive X‐ray spectroscopy results. These findings help to understand the origin of strong PMA in Mo‐based structures and show the promising prospect of using this structure for high‐packing‐density p‐MTJs and other spintronic device applications down to 10 nm scale. [ABSTRACT FROM AUTHOR]

General drawbacks of current electronic/spintronic devices are high power consumption and low density storage. A multiferroic tunnel junction (MFTJ), employing a ferroelectric barrier layer sandwiched between two ferromagnetic layers, presents four resistance states in a single device and therefore provides an alternative way to achieve high density memories. Here, an MFTJ device with eight nonvolatile resistance states by further integrating the design of noncollinear magnetization alignments between the ferromagnetic layers is demonstrated. Through the angle‐resolved tunneling magnetoresistance investigations on La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 junctions, it is found that, besides collinear parallel/antiparallel magnetic configurations, the MFTJ shows at least two other stable noncollinear (45° and 90°) magnetic configurations. Combining the tunneling electroresistance effect caused by the ferroelectricity reversal of the BaTiO3 barrier, an octonary memory device is obtained, representing potential applications in high density nonvolatile storage in the future. [ABSTRACT FROM AUTHOR]

Magnetization switching by a spin-polarized current in perpendicular anisotropy devices with magnetic nanocontact (NC) is investigated using a micromagnetic formalism. The critical switching current ( icr) and switching time ( τ0) can be reduced when a soft layer is exchange coupled to the NC. The study reveals that devices with fewer NCs have smaller icr compared to those with a large number. Furthermore, τ0 for nanoconstricted devices is almost constant with anisotropy field ( Hk), in contrast to devices without NCs that show an exponential increase with Hk. This suggests that nanoconstricted devices could be used to improve thermal stability, while reducing icr and τ0. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]