37 research outputs found
Field-Induced Magnetic Order and Simultaneous Lattice Deformation in TlCuCl3
We report the results of Cu and Cl nuclear magnetic resonance experiments
(NMR) and thermal expansion measurements in magnetic fields in the coupled
dimer spin system TlCuCl3. We found that the field-induced antiferromagnetic
transition as confirmed by the splitting of NMR lines is slightly
discontinuous. The abrupt change of the electric field gradient at the Cl
sites, as well as the sizable change of the lattice constants, across the phase
boundary indicate that the magnetic order is accompanied by simultaneous
lattice deformation.Comment: 4 pages, 5 figure
Magnetic Transformations in the Organic Conductor kappa-(BETS)2Mn[N(CN)2]3 at the Metal-Insulator Transition
A complex study of magnetic properties including dc magnetization, 1H NMR and
magnetic torque measurements has been performed for the organic conductor
kappa-(BETS)2Mn[N(CN)2]3 which undergoes a metal-insulator transition at
T_MI~25K. NMR and the magnetization data indicate a transition in the manganese
subsystem from paramagnetic to a frozen state at T_MI, which is, however, not a
simple Neel type order. Further, a magnetic field induced transition resembling
a spin flop has been detected in the torque measurements at temperatures below
T_MI. This transition is most likely related to the spins of pi-electrons
localized on the organic molecules BETS and coupled with the manganese 3d spins
via exchange interaction.Comment: 6 pages, 5 Figures, 1 Table; Submitted to Phys.Rev.B (Nov.2010
Low Temperature Symmetry of Pyrochlore Oxide Cd2Re2O7
We report the X-ray study for the pyrochlore oxide Cd2Re2O7. Two
symmetry-lowering structural transitions were observed at Ts1=200K and
Ts2=120K. The former is of the second order from the ideal cubic pyrochlore
structure with space group Fd-3m to a tetragonally distorted structure with
I-4m2, while the latter is of the first order likely to another tetragonal
space group I4122. We discuss the feature of the lattice deformation.Comment: 4 pages, 4 figure
Staggered Spin Order of Localized pi-electrons in the Insulating State of the Organic Conductor kappa-BETS)2Mn[N(CN)2]3
Magnetic properties of the conduction pi-electron system of
kappa-BETS)2Mn[N(CN)2]3 have been probed using 13C NMR. At ambient pressure,
the metal-insulator transition observed in the resistivity measurements below
T~23K is shown to be accompanied by ordering of the pi-spins in a long-range
staggered structure. As the metal-insulator transition is suppressed by
applying a small pressure of ~0.5 kbar, the pi-spin system maintains the
properties of the metallic state down to 5K.Comment: 13 pages, 4 figure
Influence of Rb, Cs and Ba on Superconductivity of Magnesium Diboride
Magnesium diboride has been thermally treated in the presence of Rb, Cs, and
Ba. Magnetic susceptibility shows onsets of superconductivity in the resulting
samples at 52K (Rb), 58K (Cs) and 45K (Ba). Room-temperature 11B NMR indicates
to cubic symmetry of the electric field gradient at boron site for the samples
reacted with Rb and Cs, in contrast to the axial symmetry in the initial MgB2
and in the sample treated with Ba.Comment: 3 pages (twocolumn), 2 figure