54 research outputs found
Interfacial mechanism in the anomalous Hall effect of Co/BiO bilayers
Oxide interfaces are a source of spin-orbit coupling which can lead to novel
spin-to-charge conversion effects. In this work the contribution of the
BiO interface to the anomalous Hall effect of Co is experimentally
studied in Co/BiO bilayers. We evidence a variation of 40% in the AHE
of Co when a BiO capping layer is added to the ferromagnet. This strong
variation is attributed to an additional source of asymmetric transport in
Co/BiO bilayers that originates from the Co/BiO interface and
contributes to the skew scattering.Comment: 7 pages, 4 figure
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
Unveiling the mechanisms of the spin Hall effect in Ta
Spin-to-charge current interconversions are widely exploited for the
generation and detection of pure spin currents and are key ingredients for
future spintronic devices including spin-orbit torques and spin-orbit logic
circuits. In case of the spin Hall effect, different mechanisms contribute to
the phenomenon and determining the leading contribution is peremptory for
achieving the largest conversion efficiencies. Here, we experimentally
demonstrate the dominance of the intrinsic mechanism of the spin Hall effect in
highly-resistive Ta. We obtain an intrinsic spin Hall conductivity for
-Ta of -820120 (/e) from spin
absorption experiments in a large set of lateral spin valve devices. The
predominance of the intrinsic mechanism in Ta allows us to linearly enhance the
spin Hall angle by tuning the resistivity of Ta, reaching up to -353%, the
largest reported value for a pure metal.Comment: 9 pages and 4 figures + Supplemental Material (2 pages, 3 figures
Estudio del daño local en un nudo viga pilar en un pórtico de hormigón armado usando el indice b-value obtenido por la energía de emisión acústica y la transformada wavelet
La técnica de Emisión Acústica (EA) ha demostrado ser eficaz para el seguimiento y la caracterización del daño en el hormigón armado. En este trabajo ha sido posible identificar las escalas (frecuencias) asignadas a la fractura del hormigón a través de la aplicación de la transformada wavelet continua (CWT) para evaluar el daño local en conexiones viga-columna de un pórtico de hormigón armado sometido a pruebas de tipo dinámicas (acciones sísmicas) con la mesa sísmica de la Universidad de Granada. Un nuevo índice de daño fue definido, denominado b-value energético a través de la Energía de Emisión Acústica calculada con la transformada wavelet. Esta energía fue obtenida mediante la reconstrucción de las señales de EA en las escalas (frecuencias) asignadas a la fractura del hormigón; de este modo, las fracturas macroscópicas en una unión viga-columna pudieron ser evaluadas en un pórtico de hormigón armado. The technique of Acoustic Emission (AE) has proven to be effective for monitoring and characterization of damage in reinforced concrete. In this work, it has been possible to identify scales (frequencies) assigned to the fracture of concrete through the application of the continuous wavelet transform (CWT), to assess local damage in beam-column connections. The dynamic loads (seismic actions) were carried out on a reinforced concrete frame with the seismic table of the University of Granada. A new damage index was defined, called Wavelet Energy b-value through the Acoustic Emission Energy calculated with the CWT. This energy was obtained by reconstructing AE signals in the scales (frequencies) assigned to the fracture of concrete; thus, macroscopic fractures in a beam- column connection could be evaluated in a reinforced concrete frame
Hanle Magnetoresistance in Thin Metal Films with Strong Spin-Orbit Coupling
We report measurements of a new type of magnetoresistance in Pt and Ta thin
films. The spin accumulation created at the surfaces of the film by the spin
Hall effect decreases in a magnetic field because of the Hanle effect,
resulting in an increase of the electrical resistance as predicted by Dyakonov
[PRL 99, 126601 (2007)]. The angular dependence of this magnetoresistance
resembles the recently discovered spin Hall magnetoresistance in Pt/Y3Fe5O12
bilayers, although the presence of a ferromagnetic insulator is not required.
We show that this Hanle magnetoresistance is an alternative, simple way to
quantitatively study the coupling between charge and spin currents in metals
with strong spin-orbit coupling.Comment: 13 pages, 3 figure
Relation between spin Hall effect and anomalous Hall effect in 3d ferromagnetic metals
We study the mechanisms of the spin Hall effect (SHE) and anomalous Hall
effect (AHE) in 3 ferromagnetic metals (Fe, Co, permalloy
(NiFe; Py), and Ni) by varying their resistivities and
temperature. At low temperatures where the phonon scattering is negligible, the
skew scattering coefficients of the SHE and AHE in Py are related to its spin
polarization. However, this simple relation breaks down for Py at higher
temperatures as well as for the other ferromagnetic metals at any temperature.
We find that, in general, the relation between the SHE and AHE is more complex,
with the temperature dependence of the SHE being much stronger than that of
AHE.Comment: 7 pages, 5 figure
New pathogenic variant in DLX5: New clues for a clinical spectrum from split-hand-foot malformation to fibular aplasia, tibial campomelia and oligosyndactyly
Introduction: FATCO (Fibular Aplasia, Tibial Campomelia and Oligosyndactyly) is a very infrequent skeletal dysplasia classified within the limb hypoplasia-reduction defects group whose genetic cause has not yet been identified. The advent of next-generation sequencing is enabling the diagnosis of diseases with no previously known genetic cause.Methods: We performed a thorough autopsy on a fetus whose pregnancy was legally terminated due to severe malformations detected by ultrasound. A trio exome was run to identify the genetic cause and risk of recurrence. Previous literature of similar cases was systematically searched.Results: Anatomopathological analyses revealed complete fibular aplasia, shortened and campomelic tibia, absent ankle joint, club right foot and a split foot malformation, leading to the diagnosis of FATCO. Exome sequencing showed that the female fetus carried a de novo nonsense variant in DLX5. The literature search permitted the collection of information on 43 patients with FATCO, the majority of whom were males diagnosed postnatally. In most cases, lower limbs were affected exclusively, but in 39.5% of cases the upper limbs were also affected.Conclusion: The pathologies associated with DLX5 variants encompass a wide spectrum of manifestations ranging from abnormalities exclusively in the hands and feet to long bones such as the tibia and fibula
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