Future applications of spin-orbit torque will require new mechanisms to improve the efficiency of switching nanoscale magnetic tunnel junctions (MTJs), while also controlling the magnetic dynamics to achieve fast nanosecond-scale performance with low-write-error rates. Here, we demonstrate a strategy to simultaneously enhance the interfacial magnetic anisotropy energy and suppress interfacial spin-memory loss by introducing subatomic and monatomic layers of Hf at the top and bottom interfaces of the ferromagnetic free layer of an in-plane magnetized three-terminal MTJ device.

We study current-induced torques in WTe2/permalloy bilayers as a function of WTe2 thickness. We measure the torques using both second-harmonic Hall and spin-torque ferromagnetic resonance techniques for samples with WTe2 thicknesses that span from 16 nm down to a single monolayer. We confirm the existence of an out-of-plane antidamping torque, and we show directly that the sign of this torque component is reversed across a monolayer step in the WTe2.

This article reviews static and dynamic interfacial effects in magnetism, focusing on interfacially driven magnetic effects and phenomena associated with spin-orbit coupling and intrinsic symmetry breaking at interfaces. It provides a historical background and literature survey, but focuses on recent progress, identifying the most exciting new scientific results and pointing to promising future research directions.

We report measurements of the frequency and temperature dependence of ferromagnetic resonance (FMR) for a 15-nm-thick yttrium iron garnet (YIG) film grown by off-axis sputtering. Although the FMR linewidth is narrow at room temperature [corresponding to a damping coefficient α=(9.0±0.2)×10-4], comparable to previous results for high-quality YIG films of similar thickness, the linewidth increases strongly at low temperatures, by a factor of almost 30. This increase cannot be explained as due to two-magnon scattering from defects at the sample interfaces.

We report on the perpendicular magnetic anisotropy (PMA) behavior of heavy metal (HM)/Fe alloy/MgO thin film heterostructures when an ultrathin HfO2 passivation layer is inserted between the Fe alloy and MgO. This is accomplished by depositing one to two atomic layers of Hf onto the Fe alloy before the subsequent rf sputter deposition of the MgO layer. This Hf layer is fully oxidized during the subsequent deposition of the MgO layer, as confirmed by X-ray photoelectron spectroscopy measurements.

We demonstrate an instrument for time-resolved magnetic imaging that is highly sensitive to the in-plane magnetization state and dynamics of thin-film bilayers of yttrium iron garnet [Y3Fe5O12(YIG)]/Pt: the time-resolved longitudinal spin Seebeck (TRLSSE) effect microscope. We detect the local in-plane magnetic orientation within the YIG by focusing a picosecond laser to generate thermally driven spin current from the YIG into the Pt by the spin Seebeck effect and then use the inverse spin Hall effect in the Pt to transduce this spin current to an output voltage.

We present a study of the magnetic dynamics associated with nanosecond scale magnetic switching driven by the spin Hall effect in 3-terminal nanoscale magnetic tunnel junctions (MTJs) with in-plane magnetization.

Recent discoveries regarding current-induced spin-orbit torques produced by heavy-metal/ferromagnet and topological-insulator/ferromagnet bilayers provide the potential for dramatically improved efficiency in the manipulation of magnetic devices. However, in experiments performed to date, spin-orbit torques have an important limitation - the component of torque that can compensate magnetic damping is required by symmetry to lie within the device plane.

We report an initial experimental survey of spin Hall torques generated by the rare-earth metals Gd, Dy, Ho, and Lu, along with comparisons to first-principles calculations of their spin Hall conductivities. Using spin torque ferromagnetic resonance (ST-FMR) measurements and dc-biased ST-FMR, we estimate lower bounds for the spin Hall torque ratio, ξSH, of ≈0.04 for Gd, ≈0.05 for Dy, ≈0.14 for Ho, and ≈0.014 for Lu.

In the past, magnetic images acquired using scanning superconducting quantum interference device (SQUID) microscopy have been interpreted using simple models for the sensor point spread function. However, more complicated modeling is needed when the characteristic dimensions of the field sensitive areas in these sensors become comparable to the London penetration depth. In this paper we calculate the response of SQUIDs with deep sub-micron pickup loops to different sources of magnetic fields by solving coupled London's and Maxwell's equations using the full sensor geometry.