46 research outputs found
Thermal expansion and effect of pressure on superconductivity in CuxTiSe2
We report measurements of thermal expansion on a number of polycrystalline
CuxTiSe2 samples corresponding to the parts of x - T phase diagram with
different ground states, as well as the pressure dependence of the
superconducting transition temperature for samples with three different values
of Cu-doping. Thermal expansion data suggest that the x - T phase diagram may
be more complex than initially reported. T_c data at elevated pressure can be
scaled to the ambient pressure CuxTiSe2 phase diagram, however, significantly
different scaling factors are needed to accommodate the literature data on the
charge density wave transition suppression under pressure
Anisotropic thermal expansion and magnetostriction of YNiBC single crystals
We present results of anisotropic thermal expansion and low temperature
magnetostriction measurements on YNiBC single crystals grown by high
temperature flux and floating zone techniques. Quantum oscillations of
magnetostriction were observed at low temperatures for starting at
fields significantly below (). Large irreversible,
longitudinal magnetostriction was seen in both, in-plane and along the c-axis,
directions of the applied magnetic field in the intermediate superconducting
state. Anisotropic uniaxial pressure dependencies of were evaluated using
results of zero field, thermal expansion measurements
High-resolution x-ray diffraction study of the heavy-fermion compound YbBiPt
YbBiPt is a heavy-fermion compound possessing significant short-range
antiferromagnetic correlations below a temperature of K,
fragile antiferromagnetic order below K, a Kondo temperature
of K, and crystalline-electric-field splitting on the
order of K. Whereas the compound has a
face-centered-cubic lattice at ambient temperature, certain experimental data,
particularly those from studies aimed at determining its
crystalline-electric-field scheme, suggest that the lattice distorts at lower
temperature. Here, we present results from high-resolution, high-energy x-ray
diffraction experiments which show that, within our experimental resolution of
\AA, no structural phase transition
occurs between and K. In combination with results from dilatometry
measurements, we further show that the compound's thermal expansion has a
minimum at K and a region of negative thermal expansion for
K. Despite diffraction patterns taken at K which indicate that
the lattice is face-centered cubic and that the Yb resides on a
crystallographic site with cubic point symmetry, we demonstrate that the linear
thermal expansion may be modeled using crystalline-electric-field level schemes
appropriate for Yb residing on a site with either cubic or less than
cubic point symmetry.Comment: 7 pages, 3 figures, submitted to Phys. Rev.
Thermal Expansion and Magnetostriction of the Ising Antiferromagnet TbNi2Ge2
We have measured the linear thermal expansion and magnetostriction of the
Ising antiferromagnet TbNi2Ge2 along its c-axis from room temperature to 2 K
and in magnetic fields to 14 T. We find a magnetic phase diagram that agrees
with earlier work and estimate aspects of its uniaxial pressure dependence. We
also find a new high field feature near 10 T which may signal the onset of an
additional field-induced phase.Comment: 2 pages, to apear in proceedings of 24th International Conference on
Low Temperature Physic
Magnetic field induced lattice anomaly inside the superconducting state of CeCoIn: evidence of the proposed Fulde-Ferrell-Larkin-Ovchinnikov state
We report high magnetic field linear magnetostriction experiments on
CeCoIn single crystals. Two features are remarkable: (i) a sharp
discontinuity in all the crystallographic axes associated with the upper
superconducting critical field that becomes less pronounced as the
temperature increases; (ii) a distinctive second order-like feature observed
only along the c-axis in the high field (10 T ) low
temperature ( 0.35 K) region. This second order transition is
observed only when the magnetic field lies within 20 of the ab-planes and
there is no signature of it above , which raises questions regarding
its interpretation as a field induced magnetically ordered phase. Good
agreement with previous results suggests that this anomaly is related to the
transition to the Fulde-Ferrel-Larkin-Ovchinnikov superconducting state.Comment: 3 figures, 5 page
Multiple regions of quantum criticality in YbAgGe
Dilation and thermopower measurements on YbAgGe, a heavy-fermion
antiferromagnet, clarify and refine the magnetic field-temperature (H-T) phase
diagram and reveal a field-induced phase with T-linear resistivity. On the
low-H side of this phase we find evidence for a first-order transition and
suggest that YbAgGe at 4.5 T may be close to a quantum critical end point. On
the high-H side our results are consistent with a second-order transition
suppressed to a quantum critical point near 7.2 T. We discuss these results in
light of global phase diagrams proposed for Kondo lattice systems