Observation of an emergent coherent state in the iron-based superconductor KFe2As2

Run Yang; Zhiping Yin; Yilin Wang; Yaomin Dai; Hu Miao; Bing Xu; Xianggang Qiu; Christopher C. Homes

doi:10.1103/PhysRevB.96.201108

Observation of an emergent coherent state in the iron-based superconductor KFe2As2

Run Yang, Zhiping Yin, Yilin Wang, Yaomin Dai, Hu Miao, Bing Xu, Xianggang Qiu, Christopher C. Homes

Research output: Contribution to journal › Article › peer-review

12 Scopus citations

Abstract

The ab-plane optical properties of KFe2As2 single crystals have been measured over a wide temperature and frequency range. Below T∗≃155 K, where this material undergoes an incoherent-coherent crossover, a new coherent response emerges in the optical conductivity. A spectral weight analysis suggests that this feature originates from high-energy bound states. Below ≃75 K the scattering rate for this feature is quadratic in temperature, indicating a Fermi-liquid response. Theoretical calculations suggest this crossover is dominated by the dxy orbital. Our results indicate Kondo-type screening is the likely mechanism for the incoherent-coherent crossover in hole-overdoped KFe2As2.

Original language	English
Article number	201108
Journal	Physical Review B
Volume	96
Issue number	20
DOIs	https://doi.org/10.1103/PhysRevB.96.201108
State	Published - Nov 14 2017
Externally published	Yes

Funding

We thank I. Zaliznyak, A. Wang, and W. Yin for useful discussions. Work at the Chinese Academy of Science was supported by NSFC (Projects No. 11374345 and No. 91421304) and MOST (Projects No. 2015CB921303 and No. 2015CB921102). Work at Beijing Normal University was supported by the National Natural Science Foundation of China (Grant No. 11674030) and the National Key Research and Development Program of China (Contract No. 2016YFA0302300). Work at Brookhaven National Laboratory was supported by the Office of Science, US Department of Energy under Contract No. DE-SC0012704. H.M. was supported by the Center for Emergent Superconductivity, an Energy Frontier Research Center funded by the US DOE, Office of Basic Energy Sciences. Y.L.W. was supported by the US Department of energy, Office of Science, Basic Energy Sciences as a part of the Computational Materials Science Program through the Center for Computational Design of Functional Strongly Correlated Materials and Theoretical Spectroscopy. The ab -plane optical properties of KFe 2 As 2 single crystals have been measured over a wide temperature and frequency range. Below T * ≃ 155 K, where this material undergoes an incoherent-coherent crossover, a new coherent response emerges in the optical conductivity. A spectral weight analysis suggests that this feature originates from high-energy bound states. Below ≃ 75 K the scattering rate for this feature is quadratic in temperature, indicating a Fermi-liquid response. Theoretical calculations suggest this crossover is dominated by the d x y orbital. Our results indicate Kondo-type screening is the likely mechanism for the incoherent-coherent crossover in hole-overdoped KFe 2 As 2 . Chinese Academy of Sciences http://dx.doi.org/10.13039/501100002367 CAS http://sws.geonames.org/1814991/ National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809 National Science Foundation of China Natural Science Foundation of China NSFC http://sws.geonames.org/1814991/ 11374345 91421304 Ministry of Science and Technology of the People's Republic of China http://dx.doi.org/10.13039/501100002855 Chinese Ministry of Science and Technology MOST http://sws.geonames.org/1814991/ 2015CB921303 2015CB921102 Beijing Normal University http://dx.doi.org/10.13039/501100002726 BNU http://sws.geonames.org/1814991/ National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809 National Science Foundation of China Natural Science Foundation of China NSFC http://sws.geonames.org/1814991/ 11674030 U.S. Department of Energy http://dx.doi.org/10.13039/100000015 DOE http://sws.geonames.org/6252001/ http://sws.geonames.org/4138106/ DE-SC0012704

Funders	Funder number
Office of Basic Energy Sciences
US Department of Energy
U.S. Department of Energy	DE-SC0012704
Office of Science
Basic Energy Sciences
National Natural Science Foundation of China	11374345 91421304, 11374345, 11674030, 91421304
Ministry of Science and Technology of the People's Republic of China	2015CB921303, 2015CB921303 2015CB921102, 2015CB921102
National Basic Research Program of China (973 Program)	2016YFA0302300

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10.1103/PhysRevB.96.201108

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title = "Observation of an emergent coherent state in the iron-based superconductor KFe2As2",

abstract = "The ab-plane optical properties of KFe2As2 single crystals have been measured over a wide temperature and frequency range. Below T∗≃155 K, where this material undergoes an incoherent-coherent crossover, a new coherent response emerges in the optical conductivity. A spectral weight analysis suggests that this feature originates from high-energy bound states. Below ≃75 K the scattering rate for this feature is quadratic in temperature, indicating a Fermi-liquid response. Theoretical calculations suggest this crossover is dominated by the dxy orbital. Our results indicate Kondo-type screening is the likely mechanism for the incoherent-coherent crossover in hole-overdoped KFe2As2.",

author = "Run Yang and Zhiping Yin and Yilin Wang and Yaomin Dai and Hu Miao and Bing Xu and Xianggang Qiu and Homes, {Christopher C.}",

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AU - Yang, Run

AU - Yin, Zhiping

AU - Wang, Yilin

AU - Dai, Yaomin

AU - Miao, Hu

AU - Xu, Bing

AU - Qiu, Xianggang

AU - Homes, Christopher C.

PY - 2017/11/14

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N2 - The ab-plane optical properties of KFe2As2 single crystals have been measured over a wide temperature and frequency range. Below T∗≃155 K, where this material undergoes an incoherent-coherent crossover, a new coherent response emerges in the optical conductivity. A spectral weight analysis suggests that this feature originates from high-energy bound states. Below ≃75 K the scattering rate for this feature is quadratic in temperature, indicating a Fermi-liquid response. Theoretical calculations suggest this crossover is dominated by the dxy orbital. Our results indicate Kondo-type screening is the likely mechanism for the incoherent-coherent crossover in hole-overdoped KFe2As2.

AB - The ab-plane optical properties of KFe2As2 single crystals have been measured over a wide temperature and frequency range. Below T∗≃155 K, where this material undergoes an incoherent-coherent crossover, a new coherent response emerges in the optical conductivity. A spectral weight analysis suggests that this feature originates from high-energy bound states. Below ≃75 K the scattering rate for this feature is quadratic in temperature, indicating a Fermi-liquid response. Theoretical calculations suggest this crossover is dominated by the dxy orbital. Our results indicate Kondo-type screening is the likely mechanism for the incoherent-coherent crossover in hole-overdoped KFe2As2.

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Observation of an emergent coherent state in the iron-based superconductor KFe2As2

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