2,721 research outputs found
Theory of Unconventional Spin Density Wave: A Possible Mechanism of the Micromagnetism in U-based Heavy Fermion Compounds
We propose a novel spin density wave (SDW) state as a possible mechanism of
the anomalous antiferromagnetism, so-called the micromagnetism, in URu_2Si_2
below 17.5[K]. In this new SDW, the electron-hole pair amplitude changes its
sign in the momentum space as in the case of the unconventional
superconductivity. It is shown that this state can be realized in an extended
Hubbard model within the mean field theory. We also examine some characteristic
properties of this SDW to compare with the experimental results. All these
properties well explain the unsolved problem of the micromagnetism.Comment: REVTeX v3.1, 4 pages, 5 figure
Resonant Inelastic X-Ray Scattering from Valence Excitations in Insulating Copper-Oxides
We report resonant inelastic x-ray measurements of insulating LaCuO
and SrCuOCl taken with the incident energy tuned near the Cu K
absorption edge. We show that the spectra are well described in a shakeup
picture in 3rd order perturbation theory which exhibits both incoming and
outgoing resonances, and demonstrate how to extract a spectral function from
the raw data. We conclude by showing {\bf q}-dependent measurements of the
charge transfer gap.Comment: minor notational changes, discussion of anderson impurity model
fixed, references added; accepted by PR
Prevalence of the HOXB13 G84E prostate cancer risk allele in men treated with radical prostatectomy
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106912/1/bju12522.pd
Identification of Non-unitary triplet pairing in a heavy Fermion superconductor UPt_3
A NMR experiment recently done by Tou et al. on a heavy Fermion
superconductor UPt is interpreted in terms of a non-unitary spin-triplet
pairing state which we have been advocating. The proposed state successfully
explains various aspects of the seemingly complicated Knight shift behaviors
probed for major orientations, including a remarkable d-vector rotation under
weak fields. This entitles UPt as the first example that a charged many
body system forms a spin-triplet odd-par ity pairing at low temperatures and
demonstrates unambiguously that the putative spin-orbit coupling in UPt is
weak.Comment: 4 pages, 2 eps figures, to be published in J. Phys. Soc. Jpn. 67
(1998) No.
Evolution of magnetic polarons and spin-carrier interactions through the metal-insulator transition in EuGdO
Raman scattering studies as functions of temperature, magnetic field, and
Gd-substitution are used to investigate the evolution of magnetic polarons and
spin-carrier interactions through the metal-insulator transition in
EuGdO. These studies reveal a greater richness of phase behavior
than have been previously observed using transport measurements: a
spin-fluctuation-dominated paramagnetic (PM) phase regime for T T
T, a two-phase regime for T T in which magnetic polarons
develop and coexist with a remnant of the PM phase, and an inhomogeneous
ferromagnetic phase regime for T T
Quantum skyrmions and the destruction of long-range antiferromagnetic order in the high-Tc superconductors La(2-x)Sr(x)CuO(4) and YBa(2)Cu(3)O(6+x)
We study the destruction of the antiferromagnetic order in the high-Tc
superconductors La(2-x)Sr(x)CuO(4) and YBa(2)Cu(3)O(6+x) in the framework of
the CP1-nonlinear sigma model formulation of the 2D quantum Heisenberg
antiferromagnet. The dopants are introduced as independent fermions with
appropriate dispersion relations determined by the shape of the Fermi surface.
The energy of skyrmion topological defects, which are shown to be introduced by
doping, is used as an order parameter for antiferromagnetic order. We obtain
analytic expressions for this as a function of doping which allow us to plot
the curves T_N(x_c)\times x_c and M(x)\times x, for both YBCO and LSCO, in good
quantitative agreement with the experimental data.Comment: 4 pages, revtex, 5 embeeded figure
Momentum-Resolved Charge Excitations in a Prototype One Dimensional Mott Insulator
We report momentum resolved charge excitations in a one dimensional (1-D)
Mott insulator studied using high resolution (~ 325 meV) inelastic x-ray
scattering over the entire Brillouin zone for the first time. Excitations at
the insulating gap edge are found to be highly dispersive (momentum
dependent)compared to excitations observed in two dimensional Mott insulators.
The observed dispersion in 1-D is consistent with charge excitations involving
holons which is unique to spin-1/2 quantum chain systems. These results point
to the potential utility of inelastic x-ray scattering in providing valuable
information about electronic structure of strongly correlated insulators.Comment: 3 pages, 2 figures, Revised with minor change
Dynamical density-density correlations in one-dimensional Mott insulators
The dynamical density-density correlation function is calculated for the
one-dimensional, half-filled Hubbard model extended with nearest neighbor
repulsion using the Lanczos algorithm for finite size systems and analytically
for large on site repulsion compared to hopping amplitudes. At the zone
boundary an excitonic feature exists for any finite nearest neighbor repulsion
and exhausts most of the spectral weight, even for parameters where no exciton
is visible at zero momentum.Comment: 5 pages, REVTeX, epsf, 3 postscript figure
Inflection point in the magnetic field dependence of the ordered moment of URu2Si2 observed by neutron scattering in fields up to 17 T
We have measured the magnetic field dependence of the ordered
antiferromagnetic moment and the magnetic excitations in the heavy-fermion
superconductor URu2Si2 for fields up to 17 Tesla applied along the tetragonal c
axis, using neutron scattering. The decrease of the magnetic intensity of the
tiny moment with increasing field does not follow a simple power law, but shows
a clear inflection point, indicating that the moment disappears first at the
metamagnetic transition at ~40 T. This suggests that the moment m is connected
to a hidden order parameter Phi which belongs to the same irreducible
representation breaking time-reversal symmetry. The magnetic excitation gap at
the antiferromagnetic zone center Q=(1,0,0) increases continuously with
increasing field, while that at Q=(1.4,0,0) is nearly constant. This field
dependence is opposite to that of the gap extracted from specific-heat data.Comment: 10 pages, 5 figures, submitted to PR
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