15,594 research outputs found
7Li NMR Studies of LiCrO2
We report on 7Li NMR studies of a spin S = 3/2 triangular lattice
antiferromagnet LiCrO2 (Neel temperature TN = 62 K) in the paramagnetic state
by using the free-induction decay of 7Li nuclear magnetization. We observed
critical divergence of the 7Li nuclear spin-lattice relaxation rate 1/T1 near
TN, a narrow critical region, and a critical exponent w = 0.45 from a fit of
1/T1 (T/TN - 1). Although spin frustration effects have been
explored for this system, the dynamical critical phenomena suggest that LiCrO2
in the critical region is a poor low dimensional antiferromagnetic system.Comment: 6 pages, 4 figures, to appear in JPS Conf. Proc. (SCES2013
Knight shift vs hole concentration in Hg1201 and Hg1212
We studied the hole concentration dependences of 63Cu Knight shifts in
single-CuO2-layer high-Tc cuprate superconductors HgBa2CuO4+d and double-layer
HgBa2CaCu2O6+d. We found that the spin Knight shift at room temperature as a
function of the hole concentration in the single-layer superconductor is
different from that in the double-layer superconductor. Two type relations
between the spin Knight shift and the hole doping level serve to estimate the
individual hole concentrations of the non-equivalent CuO2 planes in a unit
cell.Comment: 4 pages, 4 figures, submitted to Physics Procedia, ISS2014 (27th
International Symposium on Superconductivity, Tokyo
{23}Na nuclear spin-lattice relaxation studies of Na2Ni2TeO6
We report on {23}Na NMR studies of a honeycomb lattice antiferromagnet
Na2Ni2TeO6 by {23}Na nuclear spin-echo techniques. The {23}Na nuclear
spin-lattice relaxation rate 1/{23}T_1 exhibits critical divergence near a Neel
temperature T_N = 26 K, a narrow critical region, and a critical exponent w =
0.34 in 1/{23}T_1 = a (T/T_N - 1)^{-w} for Na2Ni2TeO6, and T_N = 18 K for
Na2(Ni{0.5}Cu{0.5})2TeO6. Although the uniform magnetic susceptibility of
Na2Ni2TeO6 exhibits a broad maximum at 35 K characteristic of low dimensional
spin systems, the NMR results indicate three dimensional critical phenomenon
around the Neel temperature.Comment: 4 pages, 6 figure
Site-selective Cu NMR study of the vortex cores of TlBaCuO
We report site-selective Cu NMR studies of the vortex core states of
an overdoped TlBaCuO with = 85 K. We observed
a relatively high density of low-energy quasi-particle excitations at the
vortex cores in a magnetic field of 7.4847 T along the c axis, in contrast to
YBaCuO.Comment: 5 pages, 6 figures, submitted to J. Phys. Chem. Solids (QuB2006,
Tokai
Phase Diagram of QCD at Finite Temperatures with Wilson Fermions
Phase diagram of QCD with Wilson fermions for various numbers of flavors
is discussed. Our simulations mainly performed on a lattice with the
temporal size indicate the following: The chiral phase transition is
of first order when , while it is continuous when . For
the realistic case of massless u and d quarks and the strange quark with MeV, the phase transition is first order. The sharp transition in the
intermediate mass region for at observed by the MILC group
disappears when an RG improvement is made for the pure gauge action.Comment: ps file, 7 pages with 5 figures, contribution to Lattice 94
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