640 research outputs found
Enhanced electron correlations in FeSb
FeSb has been recently identified as a new model system for studying
many-body renormalizations in a -electron based narrow gap semiconducting
system, strongly resembling FeSi. The electron-electron correlations in
FeSb manifest themselves in a wide variety of physical properties including
electrical and thermal transport, optical conductivity, magnetic
susceptibility, specific heat and so on. We review some of the properties that
form a set of experimental evidences revealing the crucial role of correlation
effects in FeSb. The metallic state derived from slight Te doping in
FeSb, which has large quasiparticle mass, will also be introduced.Comment: 9 pages, 7 figures; submitted to Annalen der Physi
Simultaneous quantization of bulk conduction and valence states through adsorption of nonmagnetic impurities on Bi2Se3
Exposing the (111) surface of the topological insulator Bi2Se3 to carbon
monoxide results in strong shifts of the features observed in angle-resolved
photoemission. The behavior is very similar to an often reported `aging' effect
of the surface and it is concluded that this aging is most likely due to the
adsorption of rest gas molecules. The spectral changes are also similar to
those recently reported in connection with the adsorption of the magnetic
adatom Fe. All spectral changes can be explained by a simultaneous confinement
of the conduction band and valence band states. This is only possible because
of the unusual bulk electronic structure of Bi2Se3. The valence band
quantization leads to spectral features which resemble those of a band gap
opening at the Dirac point.Comment: 5 pages, 4 figure
Model-free reconstruction of magnetic correlations in frustrated magnets
Frustrated magnetic systems exhibit extraordinary physical properties but
quantification of their magnetic correlations poses a serious challenge to
experiment and theory. Current insight into frustrated magnetic correlations
relies on modelling techniques such as reverse Monte Carlo methods, which
require knowledge about the exact ordered atomic structure. Here we present a
method for direct reconstruction of magnetic correlations in frustrated magnets
by three-dimensional difference pair distribution function analysis of neutron
total scattering data. The methodology is applied to the disordered frustrated
magnet bixbyite, (Mn1-xFex)2O3, which reveals nearest-neighbor
antiferromagnetic correlations for the metal sites up to a range of
approximately 15 {\AA}. Importantly, this technique allows for magnetic
correlations to be determined directly from the experimental data without any
assumption about the atomic structure
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