1,676 research outputs found
Spin pumping damping and magnetic proximity effect in Pd and Pt spin-sink layers
We investigated the spin pumping damping contributed by paramagnetic layers
(Pd, Pt) in both direct and indirect contact with ferromagnetic
NiFe films. We find a nearly linear dependence of the
interface-related Gilbert damping enhancement on the heavy-metal
spin-sink layer thicknesses t in direct-contact
NiFe/(Pd, Pt) junctions, whereas an exponential dependence is
observed when NiFe and (Pd, Pt) are separated by \unit[3]{nm} Cu.
We attribute the quasi-linear thickness dependence to the presence of induced
moments in Pt, Pd near the interface with NiFe, quantified using
X-ray magnetic circular dichroism (XMCD) measurements. Our results show that
the scattering of pure spin current is configuration-dependent in these systems
and cannot be described by a single characteristic length
Assessment of the U and Co magnetic moments in UCoGe by X-ray magnetic circular dichroism
The ferromagnetic superconductor UCoGe has been investigated by high field
X-ray magnetic circular dichroism (XMCD) at the U-M and Co/Ge-K edges.
The analysis of the branching ratio and XMCD at the U-M edges reveals
that the U-5 electrons count is close to 3. The orbital ()
and spin () moments of U at 2.1K and 17T (H//c) have been
determined. Their ratio () suggests a significant delocalization of
the 5 electron states. The similar field dependences of the local U/Co and
the macroscopic magnetization indicate that the Co moment is induced by the U
moment. The XMCD at the Co/Ge-K edges reveal the presence of small Co-4 and
Ge-4 orbital moments parallel to the macroscopic magnetization. In addition,
the Co-3 moment is estimated to be at most of the order of 0.1 at
17T. Our results rule out the possibility of an unusual polarisability of the U
and Co moments as well as their antiparallel coupling. We conclude that the
magnetism which mediates the superconductivity in UCoGe is driven by U.Comment: 4 figures + supplementary materia
Spin/orbit moment imbalance in the near-zero moment ferromagnetic semiconductor SmN
SmN is ferromagnetic below 27 K, and its net magnetic moment of 0.03 Bohr
magnetons per formula unit is one of the smallest magnetisations found in any
ferromagnetic material. The near-zero moment is a result of the nearly equal
and opposing spin and orbital moments in the 6H5/2 ground state of the Sm3+
ion, which leads finally to a nearly complete cancellation for an ion in the
SmN ferromagnetic state. Here we explore the spin alignment in this compound
with X-ray magnetic circular dichroism at the Sm L2,3 edges. The spectral
shapes are in qualitative agreement with computed spectra based on an LSDA+U
(local spin density approximation with Hubbard-U corrections) band structure,
though there remain differences in detail which we associate with the anomalous
branching ratio in rare-earth L edges. The sign of the spectra determine that
in a magnetic field the Sm 4f spin moment aligns antiparallel to the field; the
very small residual moment in ferromagnetic SmN aligns with the 4f orbital
moment and antiparallel to the spin moment. Further measurements on very thin
(1.5 nm) SmN layers embedded in GdN show the opposite alignment due to a strong
Gd-Sm exchange, suggesting that the SmN moment might be further reduced by
about 0.5 % Gd substitution
Electronic tuneability of a structurally rigid surface intermetallic and Kondo lattice: CePt / Pt(111)
We present an extensive study of structure, composition, electronic and
magnetic properties of Ce--Pt surface intermetallic phases on Pt(111) as a
function of their thickness. The sequence of structural phases appearing in low
energy electron diffraction (LEED) may invariably be attributed to a single
underlying intermetallic atomic lattice. Findings from both microscopic and
spectroscopic methods, respectively, prove compatible with CePt formation
when their characteristic probing depth is adequately taken into account. The
intermetallic film thickness serves as an effective tuning parameter which
brings about characteristic variations of the Cerium valence and related
properties. Soft x-ray absorption (XAS) and magnetic circular dichroism (XMCD)
prove well suited to trace the changing Ce valence and to assess relevant
aspects of Kondo physics in the CePt surface intermetallic. We find
characteristic Kondo scales of the order of 10 K and evidence for
considerable magnetic Kondo screening of the local Ce moments.
CePt/Pt(111) and related systems therefore appear to be promising
candidates for further studies of low-dimensional Kondo lattices at surfaces.Comment: 14 pages, 11 figure
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