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fflo
The program fflo calculates the Fulde-Ferell-Larkin-Ovchinnikov (FFLO) critical
field for s- and d-wave superconductors as a function of temperature and film
thickness.
Features and Description
The FFLO critical field is the upper critical field (magnetic field causing the
breakdown of superconductivity) of a clean quasi two-dimensional superconductor,
where the external magnetic field lies in the superconducting plane.
The difference between s- and d- wave superconductors lies in the order parameter
(energy gap). The gap of an s-wave superconductor is the same for all wave-vectors
k, while that of a d-wave superconductor has nodes and is thus a function of k.
This results in similar, but different superconducting properties, including a
slightly higher upper critical field for d-wave superconductors.
In a superconductor, two electrons with opposite spin pair up to build a so-called
Cooper-pair. When an external field is switched on, there are two mechanisms that
break up the Cooper-pair: paramagnetic and orbital pair-breaking.
Assuming that the external field lies in the superconducting plane, only
paramagnetic pair-breaking takes effect in a 2d superconductor. Increasing the film
thickness causes an increase in the orbital pair-breaking effect and reduces the
upper critical field, which means that the field, at which superconductivity breaks
down, gets smaller. The same happens when increasing the tilt-angle of the external
field from parallel to perpendicular.
Download
The latest version of fflo is 1.0.
fflo source package: fflo-v1.tar.gz
Installation
Documentation and Results
A comprehensive documentation on the mathematical and physical background and
results of the programs hc2, hc2d, fflo and free_energy can be read in the
dissertation of Sherryl Manalo
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