skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Effects of electron irradiation on resistivity and London penetration depth of Ba1-xKxFe2As2 (x <= 0.34) iron-pnictide superconductor

Abstract

Irradiation with 2.5 MeV electrons at doses up to 5.2×1019 electrons/cm2 was used to introduce pointlike defects in single crystals of Ba1-xKxFe2As2 with x=0.19 (Tc=14K),0.26 (Tc=32K), 0.32 (Tc=37K), and 0.34 (Tc=39K) to study the superconducting gap structure by probing the effect of nonmagnetic scattering on electrical resistivity ρ(T) and London penetration depth λ(T). For all compositions, the irradiation suppressed the superconducting transition temperature Tc and increased resistivity. The low-temperature behavior of λ(T) is best described by the power-law function, Δλ(T)=A(T/Tc)n. While substantial suppression of Tc supports s± pairing, in samples close to the optimal doping, x=0.26, 0.32, and 0.34, the exponent n remained high (n≥3), indicating almost exponential attenuation and thus a robust full superconducting gap. For the x=0.19 composition, which exhibits coexistence of superconductivity and long-range magnetism, the suppression of Tc was much more rapid, and the exponent n decreased toward the s± dirty limit of n=2. In this sample, the irradiation also suppressed the temperature of structural/magnetic transition Tsm from 103 to 98 K, consistent with the itinerant nature of the long-range magnetic order. Our results suggest that underdoped compositions, especially in the coexisting regime, are most susceptible to nonmagnetic scattering and imply that in multiband Ba1-xKxFe2As2 superconductors,more » the ratio of the interband to intraband pairing strength, as well as the related gap anisotropy, increases upon the departure from the optimal doping.« less

Authors:
 [1];  [2];  [1];  [1];  [1];  [1];  [3];  [3];  [1]
  1. Ames Laboratory
  2. Laboratoire des Solides Irradies
  3. Nanjing University
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1166894
Report Number(s):
IS-J 8480
Journal ID: ISSN 1098-0121; PRBMDO; ArticleNumber: 104514
DOE Contract Number:
DE-AC02-07CH11358
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 90; Journal Issue: 10
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Cho, K, Konczykowski, M, Murphy, Jason, Kim, H, Tanatar, Makariy A, Straszheim, Warren E, Shen, B, Wen, H H, and Prozorov, Ruslan. Effects of electron irradiation on resistivity and London penetration depth of Ba1-xKxFe2As2 (x <= 0.34) iron-pnictide superconductor. United States: N. p., 2014. Web. doi:10.1103/PhysRevB.90.104514.
Cho, K, Konczykowski, M, Murphy, Jason, Kim, H, Tanatar, Makariy A, Straszheim, Warren E, Shen, B, Wen, H H, & Prozorov, Ruslan. Effects of electron irradiation on resistivity and London penetration depth of Ba1-xKxFe2As2 (x <= 0.34) iron-pnictide superconductor. United States. doi:10.1103/PhysRevB.90.104514.
Cho, K, Konczykowski, M, Murphy, Jason, Kim, H, Tanatar, Makariy A, Straszheim, Warren E, Shen, B, Wen, H H, and Prozorov, Ruslan. Mon . "Effects of electron irradiation on resistivity and London penetration depth of Ba1-xKxFe2As2 (x <= 0.34) iron-pnictide superconductor". United States. doi:10.1103/PhysRevB.90.104514.
@article{osti_1166894,
title = {Effects of electron irradiation on resistivity and London penetration depth of Ba1-xKxFe2As2 (x <= 0.34) iron-pnictide superconductor},
author = {Cho, K and Konczykowski, M and Murphy, Jason and Kim, H and Tanatar, Makariy A and Straszheim, Warren E and Shen, B and Wen, H H and Prozorov, Ruslan},
abstractNote = {Irradiation with 2.5 MeV electrons at doses up to 5.2×1019 electrons/cm2 was used to introduce pointlike defects in single crystals of Ba1-xKxFe2As2 with x=0.19 (Tc=14K),0.26 (Tc=32K), 0.32 (Tc=37K), and 0.34 (Tc=39K) to study the superconducting gap structure by probing the effect of nonmagnetic scattering on electrical resistivity ρ(T) and London penetration depth λ(T). For all compositions, the irradiation suppressed the superconducting transition temperature Tc and increased resistivity. The low-temperature behavior of λ(T) is best described by the power-law function, Δλ(T)=A(T/Tc)n. While substantial suppression of Tc supports s± pairing, in samples close to the optimal doping, x=0.26, 0.32, and 0.34, the exponent n remained high (n≥3), indicating almost exponential attenuation and thus a robust full superconducting gap. For the x=0.19 composition, which exhibits coexistence of superconductivity and long-range magnetism, the suppression of Tc was much more rapid, and the exponent n decreased toward the s± dirty limit of n=2. In this sample, the irradiation also suppressed the temperature of structural/magnetic transition Tsm from 103 to 98 K, consistent with the itinerant nature of the long-range magnetic order. Our results suggest that underdoped compositions, especially in the coexisting regime, are most susceptible to nonmagnetic scattering and imply that in multiband Ba1-xKxFe2As2 superconductors, the ratio of the interband to intraband pairing strength, as well as the related gap anisotropy, increases upon the departure from the optimal doping.},
doi = {10.1103/PhysRevB.90.104514},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 10,
volume = 90,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}
  • We have performed 75As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements on single-crystalline Ba1-xKxFe2As2 for x = 0.27–1. 75As nuclear quadruple resonance frequency (νQ) increases linearly with increasing x. The Knight shift K in the normal state shows Pauli paramagnetic behavior with a weak temperature T dependence. K increases gradually with increasing x. By contrast, the nuclear spin–lattice relaxation rate 1/T1 in the normal state has a strong T dependence, which indicates the existence of large antiferomagnetic (AF) spin fluctuations for all x's. The T dependence of 1/T1 shows a gaplike behavior below approximately 100 K formore » 0.6 < x < 0.9. This behaviors is well explained by the change in the band structure with the expansion of hole Fermi surfaces and the shrinkage and disappearance of electron Fermi surfaces at the Brillouin zone (BZ) with increasing x. The anisotropy of 1/T1, represented by the ratio of 1/T1ab to 1/T1c, is always larger than 1 for all x's, which indicates that stripe-type AF fluctuations are dominant in this system. The K in the superconducting (SC) state decreases, which corresponds to the appearance of spin-singlet superconductivity. The T dependence of 1/T1 in the SC state indicates a multiple-SC-gap feature. A simple two-gap model analysis shows that the larger superconducting gap gradually decreases with increasing x from 0.27 to 1 and a smaller gap decreases rapidly and nearly vanishes for x > 0.6 where electron pockets in BZ disappear.« less
  • We use angle-resolved photoemission spectroscopy to investigate the electronic properties of the newly discovered iron-arsenic superconductor Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2} and nonsuperconducting BaFe{sub 2}As{sub 2}. Our study indicates that the Fermi surface of the undoped, parent compound BaFe{sub 2}As{sub 2} consists of hole pocket(s) at {Lambda}(0,0) and larger electron pocket(s) at X (1,0), in general agreement with full-potential linearized plane wave calculations. Upon doping with potassium, the hole pocket expands and the electron pocket becomes smaller with its bottom approaching the chemical potential. Such an evolution of the Fermi surface is consistent with hole doping within a rigid-band shiftmore » model. Our results also indicate that the full-potential linearized plane wave calculation is a reasonable approach for modeling the electronic properties of both undoped and K-doped iron arsenites.« less
  • The temperature-dependent interplane resistivity ρc(T) was measured in the hole-doped iron arsenide superconductor (Ba1-xKx)Fe2As2 over a doping range from parent compound to optimal doping at Tc≈38 K, 0≤x≤0.34. The measurements were undertaken on high-quality single crystals grown from FeAs flux. The coupled magnetic/structural transition at TSM leads to a clear accelerated decrease of ρc(T) on cooling in samples with Tc<26 K (x<0.25). This decrease in the hole-doped material is in notable contrast to the increase in ρc(T) in the electron-doped Ba(Fe1-xCox)Fe 2As2 and isoelectron-substituted BaFe2(As1-xPx)2. TSM decreases very sharply with doping, dropping from Ts=71 K to zero on increase ofmore » Tc from approximately 25 to 27 K. ρc(T) becomes linear in T close to optimal doping. The broad crossover maximum in ρc(T), found in the parent BaFe2As2 at around Tmax~200 K, shifts to higher temperature ~250 K with doping of x=0.34. The maximum shows clear correlation with the broad crossover feature found in the temperature-dependent in-plane resistivity ρa(T). The evolution with doping of Tmax in (Ba1-xKx)Fe2As2 is in notable contrast with both the rapid suppression of Tmax found in Ba(Fe1-xTx)2As2 (T=Co,Rh,Ni,Pd) and its rapid increase in BaFe2(As1-xPx)2. This observation suggests that pseudogap features are much stronger in hole-doped than in electron-doped iron-based superconductors, revealing significant electron-hole doping asymmetry similar to that in the cuprates.« less