22 research outputs found
Temperature dependence of spin diffusion length and spin Hall angle in Au and Pt
We have studied the spin transport and the spin Hall effect as a function of
temperature for platinum (Pt) and gold (Au) in lateral spin valve structures.
First, by using the spin absorption technique, we extract the spin diffusion
length of Pt and Au. Secondly, using the same devices, we have measured the
spin Hall conductivity and analyzed its evolution with temperature to identify
the dominant scattering mechanisms behind the spin Hall effect. This analysis
confirms that the intrinsic mechanism dominates in Pt whereas extrinsic effects
are more relevant in Au. Moreover, we identify and quantify the phonon-induced
skew scattering. We show that this contribution to skew scattering becomes
relevant in metals such as Au, with a low residual resistivity.Comment: 13 pages, 5 figure
Spin Hall magnetoresistance at Pt/CoFe2O4 interfaces and texture effects
We report magnetoresistance measurements on thin Pt bars grown on epitaxial
(001) and (111) CoFe2O4 (CFO) ferrimagnetic insulating films. The results can
be described in terms of the recently discovered spin Hall magnetoresistance
(SMR). The magnitude of the SMR depends on the interface preparation
conditions, being optimal when Pt/CFO samples are prepared in situ, in a single
process. The spin-mixing interface conductance, the key parameter governing SMR
and other relevant spin-dependent phenomena such as spin pumping or spin
Seebeck effect, is found to be different depending on the crystallographic
orientation of CFO, highlighting the role of the composition and density of
magnetic ions at the interface on spin mixing.Comment: 13 pages, 5 figure
Modulation of pure spin currents with a ferromagnetic insulator
We propose and demonstrate spin manipulation by magnetically controlled
modulation of pure spin currents in cobalt/copper lateral spin valves,
fabricated on top of the magnetic insulator YFeO (YIG). The
direction of the YIG magnetization can be controlled by a small magnetic field.
We observe a clear modulation of the non-local resistance as a function of the
orientation of the YIG magnetization with respect to the polarization of the
spin current. Such a modulation can only be explained by assuming a finite
spin-mixing conductance at the Cu/YIG interface, as it follows from the
solution of the spin-diffusion equation. These results open a new path towards
the development of spin logics.Comment: 5 pages and 4 figures + supplemental material (10 pages, 7 figures
Tuning the spin Hall effect of Pt from the moderately dirty to the superclean regime
We systematically measure and analyze the spin diffusion length and the spin
Hall effect in Pt with a wide range of conductivities using the spin absorption
method in lateral spin valve devices. We observe a linear relation between the
spin diffusion length and the conductivity, evidencing that the spin relaxation
in Pt is governed by the Elliott-Yafet mechanism. We find a single intrinsic
spin Hall conductivity ()
for Pt in the full range studied which is in good agreement with theory. For
the first time we have obtained the crossover between the moderately dirty and
the superclean scaling regimes of the spin Hall effect by tuning the
conductivity. This is equivalent to that obtained for the anomalous Hall
effect. Our results explain the spread of the spin Hall angle values in the
literature and find a route to maximize this important parameter.Comment: 11 pages, 4 figure
Spin Hall magnetoresistance as a probe for surface magnetization in Pt/CoFeO bilayers
We study the spin Hall magnetoresistance (SMR) in Pt grown
on CoFeO (CFO) ferrimagnetic insulating (FMI) films. A careful analysis
of the angle-dependent and field-dependent longitudinal magnetoresistance
indicates that the SMR contains a contribution that does not follow the bulk
magnetization of CFO but it is a fingerprint of the complex magnetism at the
surface of the CFO layer, thus signaling SMR as a tool for mapping surface
magnetization. A systematic study of the SMR for different temperatures and CFO
thicknesses gives us information impossible to obtain with any standard
magnetometry technique. On one hand, surface magnetization behaves
independently of the CFO thickness and does not saturate up to high fields,
evidencing that the surface has its own anisotropy. On the other hand,
characteristic zero-field magnetization steps are not present at the surface
while they are relevant in the bulk, strongly suggesting that antiphase
boundaries are the responsible of such intriguing features. In addition, a
contribution from ordinary magnetoresistance of Pt is identified, which is only
distinguishable due to the low resistivity of the grown Pt.Comment: 19 pages, 8 figures, Supplemental Materia