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Title: Antiferromagnetic spin correlations and pseudogaplike behavior in Ca(Fe 1-xCo x) 2As 2 studied by 75As nuclear magnetic resonance and anisotropic resistivity

We report 75As nuclear magnetic resonance (NMR) measurements of single-crystalline Ca(Fe 1–xCo x) 2As 2 (x=0.023, 0.028, 0.033, and 0.059) annealed at 350°C for 7 days. From the observation of a characteristic shape of 75As NMR spectra in the stripe-type antiferromagnetic (AFM) state, as in the case of x=0 (T N=170 K), clear evidence for the commensurate AFM phase transition with the concomitant structural phase transition is observed in x=0.023 (T N=106 K) and x=0.028 (T N=53 K). Through the temperature dependence of the Knight shifts and the nuclear spin lattice relaxation rates (1/T 1), although stripe-type AFM spin fluctuations are realized in the paramagnetic state as in the case of other iron pnictide superconductors, we found a gradual decrease of the AFM spin fluctuations below a crossover temperature T* that was nearly independent of Co-substitution concentration, and it is attributed to a pseudogaplike behavior in the spin excitation spectra of these systems. The T* feature finds correlation with features in the temperature-dependent interplane resistivity, ρc(T), but not with the in-plane resistivity ρa(T). The temperature evolution of anisotropic stripe-type AFM spin fluctuations is tracked in the paramagnetic and pseudogap phases by the 1/T 1 data measured under magnetic fields parallelmore » and perpendicular to the c axis. As a result, based on our NMR data, we have added a pseudogaplike phase to the magnetic and electronic phase diagram of Ca(Fe 1–xCo x) 2As 2.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
IS-J-8859
Journal ID: ISSN 1098-0121; PRBMDO
Grant/Contract Number:
AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 92; Journal Issue: 18; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society (APS)
Research Org:
Ames Lab., Ames, IA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1234536
Alternate Identifier(s):
OSTI ID: 1225392

Cui, J., Roy, B., Tanatar, M. A., Ran, S., Bud'ko, S. L., Prozorov, R., Canfield, P. C., and Furukawa, Y.. Antiferromagnetic spin correlations and pseudogaplike behavior in Ca(Fe1-xCox)2As2 studied by 75As nuclear magnetic resonance and anisotropic resistivity. United States: N. p., Web. doi:10.1103/PhysRevB.92.184504.
Cui, J., Roy, B., Tanatar, M. A., Ran, S., Bud'ko, S. L., Prozorov, R., Canfield, P. C., & Furukawa, Y.. Antiferromagnetic spin correlations and pseudogaplike behavior in Ca(Fe1-xCox)2As2 studied by 75As nuclear magnetic resonance and anisotropic resistivity. United States. doi:10.1103/PhysRevB.92.184504.
Cui, J., Roy, B., Tanatar, M. A., Ran, S., Bud'ko, S. L., Prozorov, R., Canfield, P. C., and Furukawa, Y.. 2015. "Antiferromagnetic spin correlations and pseudogaplike behavior in Ca(Fe1-xCox)2As2 studied by 75As nuclear magnetic resonance and anisotropic resistivity". United States. doi:10.1103/PhysRevB.92.184504. https://www.osti.gov/servlets/purl/1234536.
@article{osti_1234536,
title = {Antiferromagnetic spin correlations and pseudogaplike behavior in Ca(Fe1-xCox)2As2 studied by 75As nuclear magnetic resonance and anisotropic resistivity},
author = {Cui, J. and Roy, B. and Tanatar, M. A. and Ran, S. and Bud'ko, S. L. and Prozorov, R. and Canfield, P. C. and Furukawa, Y.},
abstractNote = {We report 75As nuclear magnetic resonance (NMR) measurements of single-crystalline Ca(Fe1–xCox)2As2 (x=0.023, 0.028, 0.033, and 0.059) annealed at 350°C for 7 days. From the observation of a characteristic shape of 75As NMR spectra in the stripe-type antiferromagnetic (AFM) state, as in the case of x=0 (TN=170 K), clear evidence for the commensurate AFM phase transition with the concomitant structural phase transition is observed in x=0.023 (TN=106 K) and x=0.028 (TN=53 K). Through the temperature dependence of the Knight shifts and the nuclear spin lattice relaxation rates (1/T1), although stripe-type AFM spin fluctuations are realized in the paramagnetic state as in the case of other iron pnictide superconductors, we found a gradual decrease of the AFM spin fluctuations below a crossover temperature T* that was nearly independent of Co-substitution concentration, and it is attributed to a pseudogaplike behavior in the spin excitation spectra of these systems. The T* feature finds correlation with features in the temperature-dependent interplane resistivity, ρc(T), but not with the in-plane resistivity ρa(T). The temperature evolution of anisotropic stripe-type AFM spin fluctuations is tracked in the paramagnetic and pseudogap phases by the 1/T1 data measured under magnetic fields parallel and perpendicular to the c axis. As a result, based on our NMR data, we have added a pseudogaplike phase to the magnetic and electronic phase diagram of Ca(Fe1–xCox)2As2.},
doi = {10.1103/PhysRevB.92.184504},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 18,
volume = 92,
place = {United States},
year = {2015},
month = {11}
}