Multiquantum vortices in superconductors: electronic and scanning tunneling microscopy spectra

Physical Review B - Condensed Matter and Materials Physics

Volumn 60, Issue 21, 1999, Pages 14581-14584

  Virtanen, S M M ^a   Salomaa, M M ^a  

^a AALTO UNIVERSITY   (Finland)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0000487716     PISSN: 10980121     EISSN: 1550235X     Source Type: Journal    
DOI: 10.1103/PhysRevB.60.14581     Document Type: Article

References (26)

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20. To obtain a preassigned numerical accuracy, note that both N and (Formula presented) scale linearly with (Formula presented) Due to the increase in the density of scattering states with the radius R of the computational region, the execution time varies as (Formula presented) for fixed (Formula presented) nevertheless, this is quite advantageous in comparison to the Bessel function expansion method.
21. We have also made computations with much larger (Formula presented) and (Formula presented) varying the coupling constant g, and found qualitative agreement with the results presented here.
22. The asymptotic behavior of the current density yielded (Formula presented) for temperatures (Formula presented) The fitting point (Formula presented) is a measure for the size of the vortex, ranging from (Formula presented) (Formula presented) to (Formula presented) (Formula presented) at low temperatures. Correspondingly, the maximum absolute values of the quantum number (Formula presented) for which Eq. (2) has to be solved to ensure full convergence in this region vary in the range 250–500.
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24. S. M. M. Virtanen and M. M. Salomaa (unpublished).
25. For vortices with (Formula presented) 3, or 4 flux quanta, there also occur exactly m peaks in the STM spectrum on the vortex axis as a function of the tunneling voltage. However, for larger m the outermost branches merge into the scattering continuum of the spectrum before crossing the (Formula presented) line, and the corresponding conductance maxima disappear. See also D. Rainer, J. A. Sauls, and D. Waxman, Phys. Rev. B 54, 10 094 (1996), where the local density of states for a doubly quantized vortex line has been presented at (Formula presented) within quasiclassical theory.
26. By computing the microscopic free energy of the vortices, we have demonstrated (Ref. 20) that multiquantum flux lines can be stabilized by columnar defects in conventional type II materials also near (Formula presented) (cf. Ref. 4).