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Title: Effect of equatorial line nodes on the upper critical field and London penetration depth

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 90; Journal Issue: 10; Journal ID: ISSN 1098-0121
American Physical Society
Country of Publication:
United States

Citation Formats

Kogan, V. G., and Prozorov, R.. Effect of equatorial line nodes on the upper critical field and London penetration depth. United States: N. p., 2014. Web. doi:10.1103/PhysRevB.90.100507.
Kogan, V. G., & Prozorov, R.. Effect of equatorial line nodes on the upper critical field and London penetration depth. United States. doi:10.1103/PhysRevB.90.100507.
Kogan, V. G., and Prozorov, R.. Tue . "Effect of equatorial line nodes on the upper critical field and London penetration depth". United States. doi:10.1103/PhysRevB.90.100507.
title = {Effect of equatorial line nodes on the upper critical field and London penetration depth},
author = {Kogan, V. G. and Prozorov, R.},
abstractNote = {},
doi = {10.1103/PhysRevB.90.100507},
journal = {Physical Review B},
number = 10,
volume = 90,
place = {United States},
year = {Tue Sep 23 00:00:00 EDT 2014},
month = {Tue Sep 23 00:00:00 EDT 2014}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevB.90.100507

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  • The upper critical field Hc2 and its anisotropy are calculated for order parameters with line nodes at the equators, kz=0, of the Fermi surface of uniaxial superconductors. It is shown that characteristic features found in Fe-based materials (a nearly linear Hc2(T) in a broad T domain, a low and increasing on warming anisotropy γH=Hc2,ab/Hc2,c) can be caused by competing effects of the equatorial nodes and of the Fermi surface anisotropy. For certain material parameters, γH(T)-1 may change sign upon warming, in agreement with the recorded behavior of FeTeS systems. It is also shown that the anisotropy of the penetration depthmore » γλ=λc/λab decreases upon warming to reach γH at Tc, in agreement with data available. For some materials γλ(T) may change upon warming, from γλ>1 at low Ts to γλ<1 at high Ts.« less
  • We have measured the upper critical field and the irreversibility line of grain-aligned YBa{sub 2}Cu{sub 4}O{sub 8}, with the magnetic field oriented perpendicular to the CuO{sub 2} planes. The upper critical field's slope, {ital dH}{sub {ital c}2}/{ital dT}, is {minus}1.57 T/K, corresponding to a zero-temperature Ginzburg-Landau (GL) coherence length of 19.5 A. The irreversibility line obeys a power-law behavior similar to that of 90-K YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. Using the lower-critical-field data, we obtain the zero-temperature magnetic penetration depth {lambda}{sub {ital a}{ital b}}(0)=1960 A and GL parameter {kappa}{sub {ital c}}=100.
  • The magnetic penetration depth in the vortex state of YBa{sub 2}Cu{sub 3}O{sub 6.95} has been measured as a function of temperature T and magnetic field H applied along the {cflx c} axis. The internal field distribution in single crystals was fit assuming a triangular vortex lattice with an average in-plane penetration depth {lambda}{sub ab}=({lambda}{sub a}{lambda}{sub b}){sup 1/2}=1155(3) {Angstrom}, extrapolated to T=0 and H=0; {lambda}(H,T) increases with both T and H. The large T-independent increase in {lambda}{sub ab} with H is attributed to a strong nonlinear response as a result of the unconventional pairing in the superconducting state. {copyright} {ital 1997}more » {ital The American Physical Society}« less
  • Irradiation with 1.4 GeV 208 Pb ions was used to induce artificial disorder in single crystals of iron-arsenide superconductor Ba(Fe 1 - x Co x ) 2 As 2 and to study its effects on the temperature-dependent London penetration depth and transport properties. A study was undertaken on overdoped single crystals with x = 0.108 and x = 0.127 characterized by notable modulation of the superconducting gap. Irradiation corresponding to the matching fields of B Φ = 6 T and 6.5 T with doses 2.22 × 10 11 d /cm 2 and 2.4 × 10 11 d /cm 2 ,more » respectively, suppresses the superconducting T c by approximately 0.3 to 1 K. The variation of the low-temperature penetration depth in both pristine and irradiated samples is well described by the power law Δ λ ( T ) = A T n . Irradiation increases the magnitude of the prefactor A and decreases the exponent n , similar to the effect of irradiation in optimally-doped samples. This finding supports universal s ± pairing in Ba(Fe 1 - x Co x ) 2 As 2 compounds for the entire Co doping range.« less