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Title: Pressure Dependence of Coherence-Incoherence Crossover Behavior in KFe 2As 2 Observed by Resistivity and 75As-NMR/NQR.

Abstract

We present the results of 75As nuclear magnetic resonance (NMR), nuclear quadrupole resonance (NQR), and resistivity measurements in KFe 2As 2 under pressure (p). The temperature dependence of the NMR shift, nuclear spin-lattice relaxation time (T1), and resistivity show a crossover between a high-temperature incoherent, local-moment behavior and a low-temperature coherent behavior at a crossover temperature (T *). T * is found to increase monotonically with pressure, consistent with increasing hybridization between localized 3d orbitalderived bands with the itinerant electron bands. No anomaly in T * is seen at the critical pressure pc = 1.8 GPa where a change of slope of the superconducting (SC) transition temperature Tc(p) has been observed. In contrast, Tc(p) seems to correlate with antiferromagnetic spin fluctuations in the normal state as measured by the NQR 1/T1 data, although such a correlation cannot be seen in the replacement effects of A in the KFe 2As 2 (A = K, Rb, Cs) family. In the superconducting state, two T1 components are observed at low temperatures, suggesting the existence of two distinct local electronic environments. The temperature dependence of the short T1s indicates a nearly gapless state below Tc. On the other hand, the temperature dependence of themore » long component 1/T1L implies a large reduction in the density of states at the Fermi level due to the SC gap formation. These results suggest a real-space modulation of the local SC gap structure in KFe 2As 2 under pressure.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science - Office of Basic Energy Sciences - Materials Sciences and Engineering Division
OSTI Identifier:
1425286
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review, B: Condensed Matter; Journal Volume: 97; Journal Issue: 6
Country of Publication:
United States
Language:
English

Citation Formats

Wiecki, P., Taufour, V., Chung, D. Y., Kanatzidis, M. G., Bud'ko, S. L., Canfield, P. C., and Furukawa, Y. Pressure Dependence of Coherence-Incoherence Crossover Behavior in KFe2As2 Observed by Resistivity and 75As-NMR/NQR.. United States: N. p., 2018. Web. doi:10.1103/PhysRevB.97.064509.
Wiecki, P., Taufour, V., Chung, D. Y., Kanatzidis, M. G., Bud'ko, S. L., Canfield, P. C., & Furukawa, Y. Pressure Dependence of Coherence-Incoherence Crossover Behavior in KFe2As2 Observed by Resistivity and 75As-NMR/NQR.. United States. doi:10.1103/PhysRevB.97.064509.
Wiecki, P., Taufour, V., Chung, D. Y., Kanatzidis, M. G., Bud'ko, S. L., Canfield, P. C., and Furukawa, Y. Tue . "Pressure Dependence of Coherence-Incoherence Crossover Behavior in KFe2As2 Observed by Resistivity and 75As-NMR/NQR.". United States. doi:10.1103/PhysRevB.97.064509.
@article{osti_1425286,
title = {Pressure Dependence of Coherence-Incoherence Crossover Behavior in KFe2As2 Observed by Resistivity and 75As-NMR/NQR.},
author = {Wiecki, P. and Taufour, V. and Chung, D. Y. and Kanatzidis, M. G. and Bud'ko, S. L. and Canfield, P. C. and Furukawa, Y.},
abstractNote = {We present the results of 75As nuclear magnetic resonance (NMR), nuclear quadrupole resonance (NQR), and resistivity measurements in KFe2As2 under pressure (p). The temperature dependence of the NMR shift, nuclear spin-lattice relaxation time (T1), and resistivity show a crossover between a high-temperature incoherent, local-moment behavior and a low-temperature coherent behavior at a crossover temperature (T *). T * is found to increase monotonically with pressure, consistent with increasing hybridization between localized 3d orbitalderived bands with the itinerant electron bands. No anomaly in T * is seen at the critical pressure pc = 1.8 GPa where a change of slope of the superconducting (SC) transition temperature Tc(p) has been observed. In contrast, Tc(p) seems to correlate with antiferromagnetic spin fluctuations in the normal state as measured by the NQR 1/T1 data, although such a correlation cannot be seen in the replacement effects of A in the KFe2As2 (A = K, Rb, Cs) family. In the superconducting state, two T1 components are observed at low temperatures, suggesting the existence of two distinct local electronic environments. The temperature dependence of the short T1s indicates a nearly gapless state below Tc. On the other hand, the temperature dependence of the long component 1/T1L implies a large reduction in the density of states at the Fermi level due to the SC gap formation. These results suggest a real-space modulation of the local SC gap structure in KFe2As2 under pressure.},
doi = {10.1103/PhysRevB.97.064509},
journal = {Physical Review, B: Condensed Matter},
number = 6,
volume = 97,
place = {United States},
year = {Tue Feb 13 00:00:00 EST 2018},
month = {Tue Feb 13 00:00:00 EST 2018}
}