346 research outputs found
Observation of two species of vortices in the anisotropic spin-triplet superconductor
Magnetic flux structures in single crystals of the layered spin triplet
superconductor SrRuO are studied by scanning micro SQUID Force
microscopy. Vortex chains appear as the applied field is tilted along the
in-plane direction of the superconductor. The vortex chains align along the
direction of the in-plane component of the applied magnetic field. The
decoration of in-plane vortices by crossing Abrikosov vortices is observed: two
vortex orientations are apparent simultaneously, one along the layers and the
other perpendicular to the layers. The crossing vortices appear preferentially
on the in-plane vortices
Total suppression of superconductivity by high magnetic fields in YBa2 Cu3O6.6
We have studied in fields up to 60T the variation of the transverse
magnetoresistance (MR) of underdoped YBCO6.6 crystals either pure or with Tc
reduced down to 3.5K by electron irradiation. We evidence that the normal state
MR is restored above a threshold field H'c(T), which is found to vanish at
T'c>>Tc. In the pure YBCO6.6 sample a 50 Tesla field is already required to
completely suppress the superconducting fluctuations at Tc. While disorder does
not depress the pseudogap temperature, it reduces drastically the phase
coherence established at Tc and weakly H'c(0), T'c and the onset Tnu of the
Nernst signal which are more characteristic of the 2D local pairing.Comment: 4 pages, 4 figure
Nernst effect and disorder in the normal state of high-T_{c} cuprates
We have studied the influence of disorder induced by electron irradiation on
the Nernst effect in optimally and underdoped YBa2Cu3O(7-d) single crystals.
The fluctuation regime above T_{c} expands significantly with disorder,
indicating that the T_{c} decrease is partly due to the induced loss of phase
coherence. In pure crystals the temperature extension of the Nernst signal is
found to be narrow whatever the hole doping, contrary to data reported in the
low-T_{c} cuprates families. Our results show that the presence of "intrinsic"
disorder can explain the enhanced range of Nernst signal found in the pseudogap
phase of the latter compounds.Comment: revised version. to be published in Physical Review Letter
Low energy magnetic excitation spectrum of the unconventional ferromagnet CeRhB
The magnetic excitation spectrum of the unconventional ferromagnet
CeRhB was measured by inelastic neutron scattering on single
crystal sample in the magnetically ordered and paramagnetic phases. The
spin-wave excitation spectrum evidences high exchange interaction along the
c-axis about two orders of magnitude higher than the ones in the basal plane of
the hexagonal structure. Both strong out of plane and small in plane
anisotropies are found. This latter point confirms that considering the =5/2
multiplet alone is not adequate for describing the ground state of
CeRhB. Quasielastic scattering measured above is also
strongly anisotropic between the basal plane and the c-axis and suggests
localized magnetism.Comment: 8 Figure
Momentum-resolved evolution of the Kondo lattice into 'hidden-order' in URu2Si2
We study, using high-resolution angle-resolved photoemission spectroscopy,
the evolution of the electronic structure in URu2Si2 at the Gamma, Z and X
high-symmetry points from the high-temperature Kondo-screened regime to the
low-temperature `hidden-order' (HO) state. At all temperatures and symmetry
points, we find structures resulting from the interaction between heavy and
light bands, related to the Kondo lattice formation. At the X point, we
directly measure a hybridization gap of 11 meV already open at temperatures
above the ordered phase. Strikingly, we find that while the HO induces
pronounced changes at Gamma and Z, the hybridization gap at X does not change,
indicating that the hidden-order parameter is anisotropic. Furthermore, at the
Gamma and Z points, we observe the opening of a gap in momentum in the HO
state, and show that the associated electronic structure results from the
hybridization of a light electron band with the Kondo-lattice bands
characterizing the paramagnetic state.Comment: Updated published version. Mansucript + Supplemental Material (8
pages, 9 figures). Submitted 16 September 201
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