Reprinted with permission from the American Physical Society: Azzawi, S. and Ganguly, A. and Toka c, M. and Rowan-Robinson, R.M. and Sinha, J. and Hindmarch, A.T. and Barman, A. and Atkinson, D. (2016) 'Evolution of damping in ferromagnetic/nonmagnetic thin lm bilayers as a function of nonmagnetic layer thickness.', Physical review B., 93 (5). 054402 c 2016 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modied, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. The evolution of damping in Co/Pt, Co/Au, and Ni 81 Fe 19 /Pt bilayers was studied with increasing nonmagnetic (NM) heavy-metal layer thicknesses in the range 0.2 nm t NM 10 nm, where t NM is the NM layer thickness. Magnetization precession was measured in the time domain using time-resolved magneto-optical Kerr effect magnetometry. Fitting of the data with a damped sinusoidal function was undertaken in order to extract the phenomenological Gilbert damping coefficient α. For Pt-capped Co and Ni 81 Fe 19 layers a large and complex dependence of α on the Pt layer thickness was observed, while for Au capping no significant dependence was observed. It is suggested that this difference is related to the different localized spin-orbit interaction related to intermixing and to d-d hybridization of Pt and Au at the interface with Co or Ni 81 Fe 19 . Also it was shown that damping is affected by the crystal structure differences in FM thin films and at the interface, which can modify the spin-diffusion length and the effective spin-mixing conductance. In addition to the intrinsic damping an extrinsic contribution plays an important role in the enhancement of damping when the Pt capping layer is discontinuous. The dependence of damping on the nonmagnetic layer thickness is complex but shows qualitative agreement with recent theoretical predictions.

Reprinted with permission from the American Physical Society: Physical Review Letters 115, 056601 c (2015) by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modi ed, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

No abstract

Proximity-induced magnetization (PIM) has broad implications across interface-driven spintronics applications employing spin-currents. We directly determine the scaling between PIM in Pt and the temperature-dependent interface magnetization in an adjacent ferromagnet (FM) using depthresolved magnetometry. The magnetization due to PIM does not follow the generally expected linear scaling with the FM interface magnetization, as a function of temperature. Instead, it vanishes whilst the FM interface magnetization remains. The effective magnetic susceptibilities of heavy metal (HM) layers are shown to give rise to the previously unexplained asymmetric PIM found in HM/FM/HM trilayers.

with an incorrect figure. Figure 4 has been replaced as of 2 June 2016. The figure is incorrect in the printed version of the journal; therefore for the benefit of the print readership, the figure and its caption are replicated below. FIG. 4. Schematic illustration of the growth of discontinuous to continuous NM capping layer. (a) Experimental damping data for Co/Pt and Co/Au as a function of t NM. The circular point is a literature value for pure cobalt. (b) Theoretical variation in damping data for Co/Pt and Co/Au adapted from Ref. [3] as a function of t NM .

We have studied in-plane anisotropic magnetoresistance (AMR) in cobalt films with overlayers having designed electrically interface transparency. With an electrically opaque cobalt/overlayer interface, the AMR ratio is shown to vary in inverse proportion to the cobalt film thickness; an indication that in-plane AMR is a consequence of anisotropic scattering with both volume and interfacial contributions. The interface scattering anisotropy opposes the volume scattering contribution, causing the AMR ratio to diminish as the cobalt film thickness is reduced. An intrinsic interface effect explains the significantly reduced AMR ratio in ultra-thin films.

Polarized neutron reflectometry has been used to study interface magnetism and magnetic dead layers in model amorphous CoFeB:Ta alloy thin-film multilayers with Curie temperatures tuned to be below room-temperature. This allows temperature dependent variations in the effective magnetic thickness of the film to be determined at temperatures that are a significant fraction of the Curie temperature, which cannot be achieved in the material systems used for spintronic devices. In addition to variation in the effective magnetic thickness due to compositional grading at the interface with the tantalum capping layer, the key finding is that at the interface between ferromagnetic film and GaAs(001) substrate local interfacial alloying creates an additional magnetic dead-layer. The thickness of this magnetic dead-layer is temperature dependent, which may have significant implications for elevated-temperature operation of hybrid ferromagnetic metal-semiconductor spintronic devices.

The structural and magnetic properties of amorphous thin-films with various CoFeTaB thicknesses were studied to observe magnetic phase transitions due to compositional variation through the CoFeTaB layer. The investigations of the structural properties of amorphous CoFeTaB thin-films were undertaken to confirm layer thickness, interface roughness, and their amorphous structure. Temperature dependent magnetic characterizations were performed to extract Curie temperatures of each thin-film structure, where there is evidence of more than one magnetic transition point. These transition points indicate magnetic phase transitions, which may be attributed to compositional variations across the amorphous CoFeTaB thinfilms. Investigation of diffusion process in ferromagnetic thin-films is crucial for the development of spintronic applications.