12,937 research outputs found
Equilibrium magnetization in the vicinity of the first order phase transition in the mixed state of high-Tc superconductors
We present the results of a scaling analysis of isothermal magnetization M(H)
curves measured in the mixed state of high-Tc superconductors in the vicinity
of the established first order phase transition. The most surprising result of
our analysis is that the difference between the magnetization above and below
the transition may have either sign, depending on the particular chosen sample.
We argue that this observation, based on M(H) data available in the literature,
is inconsistent with the interpretation that the well known first order phase
transition in the mixed state of high-Tc superconductors always represents the
melting transition in the vortex system.Comment: 4 pages, 5 figure
Magnetic properties of PrCu at high pressure
We report a study of the low-temperature high-pressure phase diagram of the
intermetallic compound PrCu, by means of molecular-field calculations and
Cu nuclear-quadrupole-resonance (NQR) measurements under pressure.
The pressure-induced magnetically-ordered phase can be accounted for by
considering the influence of the crystal electric field on the electron
orbitals of the Pr ions and by introducing a pressure-dependent exchange
interaction between the corresponding local magnetic moments. Our experimental
data suggest that the order in the induced antiferromagnetic phase is
incommensurate. The role of magnetic fluctuations both at high and low
pressures is also discussed.Comment: 7 pages, 6 figures, submitted to Eur. Phys. J.
Optical evidence for a spin-filter effect in the charge transport of
We have measured the optical reflectivity of
as a function of temperature between 1.5 and 300
and in external magnetic fields up to 7 . The slope at the onset of the
plasma edge feature in increases with decreasing temperature and
increasing field but the plasma edge itself does not exhibit the remarkable
blue shift that is observed in the binary compound . The analysis of
the magnetic field dependence of the low temperature optical conductivity
spectrum confirms the previously observed exponential decrease of the
electrical resistivity upon increasing, field-induced bulk magnetization at
constant temperature. In addition, the individual exponential magnetization
dependences of the plasma frequency and scattering rate are extracted from the
optical data.Comment: submitted to Phys. Rev. Let
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