TY - JOUR
T1 - Tuning the Kondo effect in Yb(Fe1-xCox)2Zn20
AU - Kong, Tai
AU - Taufour, Valentin
AU - Bud'Ko, Sergey L.
AU - Canfield, Paul C.
N1 - Funding Information:
We would like to thank U. Kaluarachichi (G.D.M.); K. Cho, G. Drachuk, B. Song, Y. Furukawa, and R. Flint for useful discussions; and W. Straszheim for WDS analysis. This work was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Science and Engineering Division. The research was performed at the Ames Laboratory, which is operated for the U.S. DOE by Iowa State University under Contract No. DE-AC02-07CH11358.
Publisher Copyright:
© 2017 American Physical Society.
PY - 2017/4/3
Y1 - 2017/4/3
N2 - We study the evolution of the Kondo effect in heavy fermion compounds, Yb(Fe1-xCox)2Zn20 (0≤x≤1), by means of temperature-dependent electric resistivity and specific heat. The ground state of YbFe2Zn20 can be well described by a Kondo model with degeneracy N = 8 and a TK∼30 K. The ground state of YbCo2Zn20 is close to a Kondo state with degeneracy N = 2 and a much lower TK∼ 2 K, even though the total crystalline electric field (CEF) splittings are similar for YbFe2Zn20 and YbCo2Zn20. Upon Co substitution, the coherence temperature of YbFe2Zn20 is suppressed, accompanied by an emerging Schottky-like feature in specific heat associated with the thermal depopulation of CEF levels upon cooling. For 0.4x 0.9, the ground state remains roughly the same, which can be qualitatively understood by Kondo effect in the presence of CEF splitting. There is no clear indication of Kondo coherence in resistivity data down to 500 mK within this substitution range. The coherence reappears at around x 0.9 and the coherence temperature increases with higher Co concentration levels.
AB - We study the evolution of the Kondo effect in heavy fermion compounds, Yb(Fe1-xCox)2Zn20 (0≤x≤1), by means of temperature-dependent electric resistivity and specific heat. The ground state of YbFe2Zn20 can be well described by a Kondo model with degeneracy N = 8 and a TK∼30 K. The ground state of YbCo2Zn20 is close to a Kondo state with degeneracy N = 2 and a much lower TK∼ 2 K, even though the total crystalline electric field (CEF) splittings are similar for YbFe2Zn20 and YbCo2Zn20. Upon Co substitution, the coherence temperature of YbFe2Zn20 is suppressed, accompanied by an emerging Schottky-like feature in specific heat associated with the thermal depopulation of CEF levels upon cooling. For 0.4x 0.9, the ground state remains roughly the same, which can be qualitatively understood by Kondo effect in the presence of CEF splitting. There is no clear indication of Kondo coherence in resistivity data down to 500 mK within this substitution range. The coherence reappears at around x 0.9 and the coherence temperature increases with higher Co concentration levels.
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U2 - 10.1103/PhysRevB.95.155103
DO - 10.1103/PhysRevB.95.155103
M3 - Article
AN - SCOPUS:85017214880
SN - 0163-1829
VL - 95
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
IS - 15
M1 - 155103
ER -