402 research outputs found
Singlet Ground State and Magnetization Plateaus in BaMnO
Magnetic susceptibility and the magnetization process have been measured in
\green polycrystal. In this compound, the magnetic manganese ion exists as
Mn in a tetrahedral environment, and thus the magnetic interaction can
be described by an S=1 Heisenberg model. The ground state was found to be a
spin singlet with an excitation gap K. Magnetization
plateaus were observed at zero and at half of the saturation magnetization.
These results indicate that the present system can be represented by a coupled
antiferromagnetic dimer model.Comment: 4 pages, 4 figures, jpsj styl
Dynamical Breaking of Charge Neutrality in Intrinsic Josephson Junctions: Common Origin for Microwave Resonant Absorptions and Multiple-Branch Structures in the I-V Characteristics
Observation of Field-Induced Transverse N\'{e}el Ordering in the Spin Gap System TlCuCl
Neutron elastic scattering experiments have been performed on the spin gap
system TlCuCl in magnetic fields parallel to the -axis. The magnetic
Bragg peaks which indicate the field-induced N\'{e}el ordering were observed
for magnetic field higher than the gap field T at with odd in the plane. The spin structure in the ordered
phase was determined. The temperature and field dependence of the Bragg peak
intensities and the phase boundary obtained were discussed in connection with a
recent theory which describes the field-induced N\'{e}el ordering as a
Bose-Einstein condensation of magnons.Comment: 4 pages, 5 eps figures, jpsj styl
Superconductivity in CVD Diamond Thin Film Well-Above Liquid Helium Temperature
Diamond has always been adored as a jewel. Even more fascinating is its
outstanding physical properties; it is the hardest material known in the world
with the highest thermal conductivity. Meanwhile, when we turn to its
electrical properties, diamond is a rather featureless electrical insulator.
However, with boron doping, it becomes a p-type semiconductor, with boron
acting as a charge acceptor. Therefore the recent news of superconductivity in
heavily boron-doped diamond synthesized by high pressure sintering was received
with considerable surprise. Opening up new possibilities for diamond-based
electrical devices, a systematic investigation of these phenomena clearly needs
to be achieved. Here we show unambiguous evidence of superconductivity in a
diamond thin film deposited by a chemical vapor deposition (CVD) method.
Furthermore the onset of the superconducting transition is found to be 7.4K,
which is higher than the reported value in ref(7) and well above helium liquid
temperature. This finding establishes the superconductivity to be a universal
property of boron-doped diamond, demonstrating that device application is
indeed a feasible challenge.Comment: 6 pages, 3 figure
Superconducting anisotropy and evidence for intrinsic pinning in single crystalline MgB
We examine the superconducting anisotropy
of a metallic high- superconductor MgB by measuring the magnetic
torque of a single crystal. The anisotropy does not depend
sensitively on the applied magnetic field at 10 K. We obtain the anisotropy
parameter . The torque curve shows the sharp
hysteresis peak when the field is applied parallel to the boron layers. This
comes from the intrinsic pinning and is experimental evidence for the
occurrence of superconductivity in the boron layers.Comment: REVTeX 4, To be published in Physical Review
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