44,062 research outputs found
Nonlinear paramagnetic magnetization in the mixed state of CeCoIn_5
Torque and magnetization measurements in magnetic fields up to 14 T were
performed on CeCoIn single crystals. The amplitude of the paramagnetic
torque shows an dependence in the mixed state and an
dependence in the normal state. In addition, the mixed-state magnetizations for
both and axes show anomalous behavior after the
subtraction of the corresponding paramagnetic contributions as linear
extrapolations of the normal-state magnetization. These experimental results
point towards a nonlinear paramagnetic magnetization in the mixed state of
CeCoIn, which is a result of the fact that both orbital and Pauli limiting
effects dominate in the mixed state.Comment: 2 pages, 2 figures, conferenc
Baryon states with open charm in the extended local hidden gauge approach
In this paper we examine the interaction of and states,
together with their coupled channels, by using an extension of the local hidden
gauge formalism from the light meson sector, which is based on heavy quark spin
symmetry. The scheme is based on the use of the impulse approximation at the
quark level, with the heavy quarks acting as spectators, which occurs for the
dominant terms where there is the exchange of a light meson. The pion exchange
and the Weinberg-Tomozawa interactions are generalized and with this dynamics
we look for states generated from the interaction, with a unitary coupled
channels approach that mixes the pseudoscalar-baryon and vector-baryon states.
We find two states with nearly zero width which are associated to the
and . The lower state, with ,
couples to and , and the second one, with , to . In addition to these two states, we find four more states with
, one of them nearly degenerate in two states of .
Furthermore we find three states in , two of them degenerate in .Comment: v3: version to appear in Eur.Phys.J.
Description of as a system with the fixed center approximation
We study the system with an aim to describe the
resonance. The chiral unitary approach has achieved success in a description of
systems of the light hadron sector. With this method, the system in
the isospin sector , is found to be a dominant component of the resonance. Therefore, by regarding the system as a cluster,
the resonance, we evaluate the system applying the
fixed center approximation to the Faddeev equations. We construct the
unitarized amplitude using the chiral unitary approach. As a result, we find a
peak in the three-body amplitude around 1739 MeV and a width of about 227 MeV.
The effect of the width of and is also discussed. We
associate this peak to the which has a mass of MeV
and a width of MeV
Anomalous Paramagnetic Magnetization in Mixed State of CeCoIn single crystals
Magnetization and torque measurements were performed on CeCoIn single
crystals to study the mixed-state thermodynamics. These measurements allow the
determination of both paramagnetic and vortex responses in the mixed-state
magnetization. The paramagnetic magnetization is suppressed in the mixed state
with the spin susceptibility increasing with increasing magnetic field. The
dependence of spin susceptibility on magnetic field is due to the fact that
heavy electrons contribute both to superconductivity and paramagnetism and a
large Zeeman effect exists in this system. No anomaly in the vortex response
was found within the investigated temperature and field range
Stray field and superconducting surface spin valve effect in LaCaMnO/YBaCuO bilayers
Electronic transport and magnetization measurements were performed on
LaCaMnO/YBaCuO (LCMO/YBCO) bilayers
below the superconducting transition temperature in order to study the
interaction between magnetism and superconductivity. This study shows that a
substantial number of weakly pinned vortices are induced in the YBCO layer by
the large out-of-plane stray field in the domain walls. Their motion gives rise
to large dissipation peaks at the coercive field. The angular dependent
magnetoresistance (MR) data reveal the interaction between the stripe domain
structure present in the LCMO layer and the vortices and anti-vortices induced
in the YBCO layer by the out-of-plane stray field. In addition, this study
shows that a superconducting surface spin valve effect is present in these
bilayers as a result of the relative orientation between the magnetization at
the LCMO/YBCO interface and the magnetization in the interior of the LCMO layer
that can be tuned by the rotation of a small . This latter finding will
facilitate the development of superconductive magnetoresistive memory devices.
These low-magnetic field MR data, furthermore, suggest that triplet
superconductivity is induced in the LCMO layer, which is consistent with recent
reports of triplet superconductivity in LCMO/YBCO/LCMO trilayers and LCMO/YBCO
bilayers.Comment: 14 pages, 3 figure
Pairing Symmetry of CeCoIn Detected by In-plane Torque Measurements
In-plane torque measurements were performed on heavy fermion CeCoIn
single crystals in the temperature range 1.8 K K and
applied magnetic field up to 14 T. The normal-state torque is given by
. The reversible part of the
mixed-state torque, obtained after subtracting the corresponding normal state
torque, shows also a four-fold symmetry. In addition, sharp peaks are present
in the irreversible torque at angles of 4, 3/4, 5/4, 7/4,
etc. Both the four-fold symmetry in the reversible torque and the sharp peaks
in the irreversible torque of the mixed state imply symmetry of the
superconducting order parameter. The field and temperature dependences of the
reversible mixed-state torque provide further evidence for wave
symmetry. The four-fold symmetry in the normal state has a different origin
since it has different field and temperature dependences than the one in the
mixed state. The possible reasons of the normal state four-fold symmetry are
discussed
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