Low temperature London penetration depth and superfluid density in Fe-based superconductors

Thumbnail Image
Date
2013-01-01
Authors
Kim, Hyunsoo
Major Professor
Advisor
Ruslan Prozorov
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Research Projects
Organizational Units
Organizational Unit
Physics and Astronomy
Physics and astronomy are basic natural sciences which attempt to describe and provide an understanding of both our world and our universe. Physics serves as the underpinning of many different disciplines including the other natural sciences and technological areas.
Journal Issue
Is Version Of
Versions
Series
Abstract

The superconducting gap symmetry of the Fe-based superconductors was studied by measurements and analysis of London penetration depth and superfluid density. Tunnel diode resonator technique for these measurements was implemented in a dilution refrigerator allowing for the temperatures down to 50 mK. For the analysis of the superfluid density, we used both experimental studies of Al-coated samples and original thermodynamic approach based on Rutgers relation. In three systems studied, we found that the superconducting gap at the optimal doping is best described in multi-gap full gap scenario. By performing experiments on samples with artificially introduced disorder with heavy ion irradiation, we show that evolution of the superconducting transition temperature and of the superfluid density are consistent with full-gap sign changing s± superconducting state. The superconducting gap develops strong modulation both in the under-doped and the over-doped regimes. In the terminal hole-doped KFe2As2, both temperature dependence of the superfluid density and its evolution with increase of the scattering rate are consistent with symmetry imposed vertical line nodes in the superconducting gap. By comparative studies of hole-doped (Ba,K)Fe2As2 and electron-doped Ca10-3-8, we show that the superconducting gap modulation in the under-doped regime is intrinsic and is not induced by the coexisting static magnetic order.

Comments
Description
Keywords
Citation
DOI
Source
Subject Categories
Copyright
Tue Jan 01 00:00:00 UTC 2013