843 research outputs found
From first-order magneto-elastic to magneto-structural transition in (Mn,Fe)1.95P0.50Si0.50 compounds
We report on structural, magnetic and magnetocaloric properties of
MnxFe1.95-xP0.50Si0.50 (x > 1.10) compounds. With increasing the Mn:Fe ratio, a
first-order magneto-elastic transition gradually changes into a first-order
magneto-structural transition via a second-order magnetic transition. The study
also shows that thermal hysteresis can be tuned by varying the Mn:Fe ratio.
Small thermal hysteresis (less than 1 K) can be obtained while maintaining a
giant magnetocaloric effect. This achievement paves the way for real
refrigeration applications using magnetic refrigerants.Comment: 4 pages, 3 figures, Supplemental Materia
Universal temperature scaling of flux line pinning in high-temperature superconducting thin films
Dissipation-free current transport in high-temperature superconductors is one
of the most crucial properties of this class of materials which is directly
related to the effective inhibition of flux line movement by defect structures.
In this respect epitaxially grown thin films of YBa2Cu3O7-d (YBCO) are proving
to be the strongest candidates for many widescale applications that are close
to realization. We show that the relation between different defect structures
and flux line pinning in these films exhibits universal features which are
clearly displayed in a detailed analysis of the temperature-dependent behaviour
of local critical currents. This allows us to identify different pinning
mechanisms at different temperatures to be responsible for the found critical
currents. Additionally, the presence of grain boundaries with very low
misorientation angles affects the temperature stability of the critical
currents which has important consequences for future applications.Comment: 5 pages, 4 figures To be published in Journal of Physics: Condensed
matte
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
- âŠ