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Title: Tuning the Kondo effect in Yb(Fe 1-xCo x) 2Zn 20

We study the evolution of the Kondo effect in heavy fermion compounds, Yb(Fe 1-xCo x) 2Zn 20 (0 ≲ x ≲ 1), by means of temperature-dependent electric resistivity and speci c heat. The ground state of YbFe 2Zn 20 can be well described by a Kondo model with degeneracy N = 8 and a T K ~30 K. In the presence of a very similar total CEF splitting with YbFe 2Zn 20, the ground state of YbCo 2Zn 20 is close to a Kondo state with degeneracy N = 2 and a much lower TK ~ 2 K. Upon Co substitution, the coherence temperature of YbFe 2Zn 20 is suppressed, accompanied by an emerging Schottky-like feature in speci c heat associated with the thermal depopulation of CEF levels upon cooling. For 0.4 ≲ x ≲ 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 observable in resistivity within this substitution range down to 500 mK. The coherence re-appears at around x≳ 0.9 and the coherence temperature increases with higher Co concentration levels.
Authors:
 [1] ;  [1] ;  [1] ;  [1]
  1. Ames Lab., Ames, IA (United States)
Publication Date:
Report Number(s):
IS-J 9349
Journal ID: ISSN 2469-9950; PRBMDO; TRN: US1702648
Grant/Contract Number:
DE-AC02-07CH11358; AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 95; Journal Issue: 15; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
OSTI Identifier:
1368054
Alternate Identifier(s):
OSTI ID: 1349700

Kong, Tai, Taufour, Valentin, Bud'ko, Sergey L., and Canfield, Paul C.. Tuning the Kondo effect in Yb(Fe1-xCox)2Zn20. United States: N. p., Web. doi:10.1103/PhysRevB.95.155103.
Kong, Tai, Taufour, Valentin, Bud'ko, Sergey L., & Canfield, Paul C.. Tuning the Kondo effect in Yb(Fe1-xCox)2Zn20. United States. doi:10.1103/PhysRevB.95.155103.
Kong, Tai, Taufour, Valentin, Bud'ko, Sergey L., and Canfield, Paul C.. 2017. "Tuning the Kondo effect in Yb(Fe1-xCox)2Zn20". United States. doi:10.1103/PhysRevB.95.155103. https://www.osti.gov/servlets/purl/1368054.
@article{osti_1368054,
title = {Tuning the Kondo effect in Yb(Fe1-xCox)2Zn20},
author = {Kong, Tai and Taufour, Valentin and Bud'ko, Sergey L. and Canfield, Paul C.},
abstractNote = {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 speci c heat. The ground state of YbFe2Zn20 can be well described by a Kondo model with degeneracy N = 8 and a TK ~30 K. In the presence of a very similar total CEF splitting with YbFe2Zn20, the ground state of YbCo2Zn20 is close to a Kondo state with degeneracy N = 2 and a much lower TK ~ 2 K. Upon Co substitution, the coherence temperature of YbFe2Zn20 is suppressed, accompanied by an emerging Schottky-like feature in speci c heat associated with the thermal depopulation of CEF levels upon cooling. For 0.4 ≲ x ≲ 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 observable in resistivity within this substitution range down to 500 mK. The coherence re-appears at around x≳ 0.9 and the coherence temperature increases with higher Co concentration levels.},
doi = {10.1103/PhysRevB.95.155103},
journal = {Physical Review B},
number = 15,
volume = 95,
place = {United States},
year = {2017},
month = {4}
}