81 research outputs found
Ambivalence of the anisotropy of the vortex lattice in an anisotropic type-II superconductor
We present a geometry-based discussion of possible vortex configurations in
the mixed state of anisotropic type-II superconductors. It is shown that, if
energy considerations assign six nearest neighbors to each vortex, two distinct
modifications of the vortex lattice are possible. It is expected that certain
conditions lead to a first order phase transition from one modification of the
vortex lattice to the other upon varying the external magnetic field.Comment: 3 pages, 2 figure
Asymmetric Heat Flow in Mesoscopic Magnetic System
The characteristics of heat flow in a coupled magnetic system are studied.
The coupled system is composed of a gapped chain and a gapless chain. The
system size is assumed to be quite small so that the mean free path is
comparable to it. When the parameter set of the temperatures of reservoirs is
exchanged, the characteristics of heat flow are studied with the Keldysh Green
function technique. The asymmetry of current is found in the presence of a
local equilibrium process at the contact between the magnetic systems. The
present setup is realistic and such an effect will be observed in real
experiments. We also discuss the simple phenomenological explanation to obtain
the asymmetry.Comment: 13 pages, 3 figure
Evidence for Ballistic Thermal Conduction in the One-Dimensional S=1/2 Heisenberg Antiferromagnetic Spin System Sr2CuO3
We have measured the thermal conductivity of the one-dimensional (1D) S=1/2
Heisenberg antiferromagnetic spin system of Sr2Cu1-xPdxO3 single crystals
including nonmagnetic impurities of Pd2+. It has been found that the mean free
path of spinons along the 1D spin chain at low temperatures is very close to
the average length of finite spin chains between spin defects estimated from
the magnetic susceptibility measurements. This proves that the thermal
conduction due to spinons at low temperatures in Sr2CuO3 is ballistic as
theoretically expected [Zotos et al.: Phys. Rev. Lett. 55 (1997) 11029]
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