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$^{75}$As NMR of Ba(Fe$_{0.93}$Co$_{0.07}$)$_{2}$As$_{2}$ in High Magnetic Field
- Source :
- Phys. Rev. B 83, 214501 (2011)
- Publication Year :
- 2011
-
Abstract
- The superconducting state of an optimally doped single crystal of Ba(Fe$_{0.93}$Co$_{0.07}$)$_2$As$_2$ was investigated by $^{75}$As NMR in high magnetic fields from 6.4 T to 28 T. It was found that the Knight shift is least affected by vortex supercurrents in high magnetic fields, $H>11$ T, revealing slow, possibly higher order than linear, increase with temperature at $T \lesssim 0.5 \, T_c$, with $T_c \approx 23 \, K$. This is consistent with the extended s-wave state with $A_{1g}$ symmetry but the precise details of the gap structure are harder to resolve. Measurements of the NMR spin-spin relaxation time, $T_2$, indicate a strong indirect exchange interaction at all temperatures. Below the superconducting transition temperature vortex dynamics lead to an anomalous dip in $T_2$ at the vortex freezing transition from which we obtain the vortex phase diagram up to $H = 28$ T.<br />Comment: 13 pages, 9 figures
- Subjects :
- Condensed Matter - Superconductivity
Subjects
Details
- Database :
- arXiv
- Journal :
- Phys. Rev. B 83, 214501 (2011)
- Publication Type :
- Report
- Accession number :
- edsarx.1101.1021
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PhysRevB.83.214501