1,950 research outputs found
Duality between Topologically Massive and Self-Dual models
We show that, with the help of a general BRST symmetry, different theories in
3 dimensions can be connected through a fundamental topological field theory
related to the classical limit of the Chern-Simons model.Comment: 13 pages, LaTe
Stability of 3D Cubic Fixed Point in Two-Coupling-Constant \phi^4-Theory
For an anisotropic euclidean -theory with two interactions [u
(\sum_{i=1^M {\phi}_i^2)^2+v \sum_{i=1}^M \phi_i^4] the -functions are
calculated from five-loop perturbation expansions in
dimensions, using the knowledge of the large-order behavior and Borel
transformations. For , an infrared stable cubic fixed point for
is found, implying that the critical exponents in the magnetic phase
transition of real crystals are of the cubic universality class. There were
previous indications of the stability based either on lower-loop expansions or
on less reliable Pad\'{e approximations, but only the evidence presented in
this work seems to be sufficently convincing to draw this conclusion.Comment: Author Information under
http://www.physik.fu-berlin.de/~kleinert/institution.html . Paper also at
http://www.physik.fu-berlin.de/~kleinert/kleiner_re250/preprint.htm
Magnetocaloric effect and improved relative cooling power in (La0.7Sr0.3MnO3/SrRuO3) superlattices
Magnetic properties of a series of (La0.7Sr0.3MnO3/SrRuO3) superlattices,
where the SrRuO3 layer thickness is varying, are examined. A room-temperature
magnetocaloric effect is obtained owing to the finite size effect which reduces
the TC of La0.7Sr0.3MnO3 layers. While the working temperature ranges are
enlarged,, -DeltaSmax values remains similar to the values in polycrystalline
La0.7Sr0.3MnO3. Consequently, the relative cooling powers are significantly
improved, the microscopic mechanism of which is related to the effect of the
interfaces at La0.7Sr0.3MnO3/SrRuO3 and higher nanostructural disorder. This
study indicates that artificial oxide superlattices/multilayers might provide
an alternative pathway in searching for efficient room-temperature magnetic
refrigerators for (nano)microscale systems.Comment: 14^pages, 3 figures, Submitted to J. Phys. Cond. Ma
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