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Title: Super-heavy electron material as metallic refrigerant for adiabatic demagnetization cooling

Low-temperature refrigeration is of crucial importance in fundamental research of condensed matter physics, because the investigations of fascinating quantum phenomena, such as superconductivity, superfluidity, and quantum criticality, often require refrigeration down to very low temperatures. Currently, cryogenic refrigerators with 3He gas are widely used for cooling below 1 Kelvin. However, usage of the gas has been increasingly difficult because of the current world-wide shortage. Therefore, it is important to consider alternative methods of refrigeration. We show that a new type of refrigerant, the super-heavy electron metal YbCo 2Zn 20, can be used for adiabatic demagnetization refrigeration, which does not require 3He gas. This method has a number of advantages, including much better metallic thermal conductivity compared to the conventional insulating refrigerants. We also demonstrate that the cooling performance is optimized in Yb 1$-$xSc xCo 2Zn 20 by partial Sc substitution, with x ~ 0.19. The substitution induces chemical pressure that drives the materials to a zero-field quantum critical point. This leads to an additional enhancement of the magnetocaloric effect in low fields and low temperatures, enabling final temperatures well below 100 mK. This performance has, up to now, been restricted to insulators. For nearly a century, the same principle ofmore » using local magnetic moments has been applied for adiabatic demagnetization cooling. Lastly, this study opens new possibilities of using itinerant magnetic moments for cryogen-free refrigeration.« less
 [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [4]
  1. Gottingen Univ. (Germany). I. Physikalisches Inst.; Kyoto Univ. (Japan). Dept. of Physics; Univ. of Augsburg (Germany). Experimental Physics VI, Center for Electronic Correlations and Magnetism
  2. Gottingen Univ. (Germany). I. Physikalisches Inst.
  3. Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy
  4. Gottingen Univ. (Germany). I. Physikalisches Inst.; Univ. of Augsburg (Germany). Experimental Physics VI, Center for Electronic Correlations and Magnetism
Publication Date:
Report Number(s):
Journal ID: ISSN 2375-2548
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Science Advances
Additional Journal Information:
Journal Volume: 2; Journal Issue: 9; Journal ID: ISSN 2375-2548
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; Adiabatic demagnetization refrigeration; heavy fermion; quantum critical point
OSTI Identifier: