J. B. S. Mendes

Tunable misalignment of ferromagnetic and antiferromagnetic easy axes in exchange biased bilayers

In this paper we report experiments that show how to tune the unidirectional anisotropy field in exchange biased Ni81Fe19/Ir20Mn80 bilayers grown by sputtering. During growth the samples are held in an obliquely inclined stage, and simultaneously a static magnetic field is applied along an arbitrary direction in the film plane. While the direction of the ferromagnetic anisotropy field is given by the tilted columnar microstructures induced by the oblique sputtering, the direction of the unidirectional field can be tuned by the application of the in situ magnetic field. The magnetic properties were investigated using the ferromagnetic resonance technique.

Possible Interplay Between Intrinsic and Extrinsic Ferromagnetic Damping Mechanisms

Here we present a ferromagnetic resonance investigation in which we measure the resonance field and linewidth in a series of films that were fabricated by oblique sputtering deposition. From the angular dependence of the resonance field we were able to extract the uniaxial anisotropy field. We show that microstructures that grow in the inclined films, induce very strong uniaxial anisotropy field values that vary from ~0 Oe to around 300 Oe, for deposition angles varying from 0° to 70°. From the angular dependence of the linewidth we were also able to investigate the spin relaxation mechanisms existent in these films. From the measurements it is possible to separate the contributions from intrinsic (Gilbert parameter) and extrinsic (two-magnon) relaxation processes. For films grown at deposition angles between 0° and 40° the Gilbert parameter ¿ value keeps an almost fixed value of 0.011 while the two-magnon contribution is negligible. For films grown at the oblique angle of 40° the Gilbert parameter ¿ abruptly decreases to 0.008 and the two-magnons parameter ¿¿ suddenly jumps to almost 1.0 GHz. For films grown at angles bigger than 40°, ¿ monotonically increases and the two-magnon parameter contribution monotonically decreases.

Observation of magnons in Mn2Au films by inelastic Brillouin and Raman light scattering

The intermetallic antiferromagnetic compound Mn2Au has been attracting considerable interest for antiferromagnetic spintronics due to its high Neel temperature and strong spin–orbit coupling. We report on the experimental investigation of the zero-wave number magnon frequencies in Mn2Au films using Brillouin and Raman inelastic light scattering techniques. The derived effective anisotropy field values are in close agreement with theoretical calculations. With the values of the anisotropy and exchange fields, the full magnon dispersion curves in Mn2Au were calculated. Due to the weak in-plane anisotropy, the k ∼ 0 frequency of the lower magnon branch, 121 GHz, is among the lowest for 3D antiferromagnets, suggesting that Mn2Au is a good candidate for realizing the generation of spin currents by antiferromagnetic resonance driven spin-pumping, as proposed theoretically.

Dirac-surface-state-dominated spin to charge current conversion in the topological insulator ( Bi0.22Sb0.78)2Te3 films at room temperature

We report the spin to charge current conversation in an intrinsic topological insulator (TI)

Spin Seebeck effect in the antiferromagnet nickel oxide at room temperature

(Bi_{0.22}Sb_{0.78})_2Te_3

Giant Zeeman shifts in the optical transitions of yttrium iron garnet thin films

film at room temperature. The spin currents are generated in a thin layer of permalloy (Py) by two different processes, spin pumping (SPE) and spin Seebeck effects (SSE). In the first we use microwave-driven ferromagnetic resonance of the Py film to generate a SPE spin current that is injected into the TI

Efficient spin to charge current conversion in the 2D semiconductor MoS2 by spin pumping from yttrium iron garnet

(Bi_{0.22}Sb_{0.78})_2Te_3

Large inverse spin Hall effect in the antiferromagnetic metalIr20Mn80

layer in direct contact with Py. In the second we use the SSE in the longitudinal configuration in Py without contamination by the Nernst effect made possible with a thin NiO layer between the Py and

Electrical detection of ferromagnetic resonance in single layers of permalloy: Evidence of magnonic charge pumping

(Bi_{0.22}Sb_{0.78})_2Te_3

Longitudinal spin Seebeck effect in permalloy separated from the anomalous Nernst effect: Theory and experiment

layers. The spin-to-charge current conversion is attributed to the inverse Edelstein effect (IEE) made possible by the spin-momentum locking in the electron Fermi contours due to the Rashba field. The measurements by the two techniques yield very similar values for the IEE parameter, which are larger than the reported values in the previous studies on topological insulators.