217 research outputs found
Uncovering the Hidden Order in URu2Si2 by Impurity Doping
We report the use of impurities to probe the hidden order parameter of the
strongly correlated metal URu_2Si_2 below the transition temperature T_0 ~ 17.5
K. The nature of this order parameter has eluded researchers for more than two
decades, but is accompanied by the development of a partial gap in the single
particle density of states that can be detected through measurements of the
electronic specific heat and nuclear spin-lattice relaxation rate. We find that
impurities in the hidden order phase give rise to local patches of
antiferromagnetism. An analysis of the coupling between the antiferromagnetism
and the hidden order reveals that the former is not a competing order parameter
but rather a parasitic effect of the latter.Comment: 4 pages, 4 figure
Stripes Disorder and Correlation lengths in doped antiferromagnets
For stripes in doped antiferromagnets, we find that the ratio of spin and
charge correlation lenghts, , provide a sharp criterion for
determining the dominant form of disorder in the system. If stripes disorder is
controlled by topological defects then . In contast,
if stripes correlations are disordered primarily by non-topological elastic
deformations (i.e., a Bragg-Glass type of disorder) then is expected. Therefore, the observation of in and in invariably implies that the stripes
are in a Bragg glass type state, and topological defects are much less relevant
than commonly assumed. Expected spectral properties are discussed. Thus, we
establish the basis for any theoretical analysis of the experimentally
obsereved glassy state in these material.Comment: 4 pages, 2 figure
Coulomb-U and magnetic moment collapse in -Pu
The around-the-mean-field version of the LDA+U method is applied to
investigate electron correlation effects in -Pu. It yields a
non-magnetic ground state of Pu, and provides a good agreement with
experimental equilibrium volume, bulk modulus and explains important features
of the photoelectron spectra
Nature of non-magnetic strongly-correlated state in delta-plutonium
Ab-initio relativistic dynamical mean-field theory is applied to resolve the
long-standing controversy between theory and experiment in the "simple"
face-centered cubic phase of plutonium called delta-Pu. In agreement with
experiment, neither static nor dynamical magnetic moments are predicted. In
addition, the quasiparticle density of states reproduces not only the peak
close to the Fermi level, which explains the large coefficient of electronic
specific heat, but also main 5f features observed in photoelectron
spectroscopy.Comment: 9 pages, 3 figure
Complex Landau Ginzburg Theory of the Hidden Order in URu_2Si_2
We develop a Landau Ginzburg theory of the hidden order phase and the local
moment antiferromagnetic phase of URu_2Si_2. We unify the two broken symmetries
in a common complex order parameter and derive many experimentally relevant
consequences such as the topology of the phase diagram in magnetic field and
pressure. The theory accounts for the appearance of a moment under application
of stress and the thermal expansion anomaly across the phase transitions. It
identifies the low energy mode which is seen in the hidden order phase near the
conmensurate wavector (0,0, 1) as the pseudo-Goldstone mode of the approximate
U(1) symmetry.Comment: 4 pages, 3 figure
Weak Pseudogap Behavior in the Underdoped Cuprate Superconductors
We report on an exact solution of the nearly antiferromagnetic Fermi liquid
spin fermion model in the limit \pi T << \omega_{sf}, which demonstrates that
the broad high energy features found in ARPES measurements of the spectral
density of the underdoped cuprate superconductors are determined by strong
antiferromagnetic (AF) correlations and precursor effects of an SDW state. We
show that the onset temperature, T^{cr}, of weak pseudo-gap (pseudoscaling)
behavior is determined by the strength, \xi, of the AF correlations, and obtain
the generic changes in low frequency magnetic behavior seen in NMR experiments
with \xi(T^{cr}) \approx 2, confirming the Barzykin and Pines crossover
criterion.Comment: REVTEX, 4 pages, 3 EPS figure
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