Campus Units

Physics and Astronomy, Ames Laboratory

Document Type

Article

Publication Version

Published Version

Publication Date

9-9-2016

Journal or Book Title

Science Advances

Volume

2

Issue

9

First Page

e1600835

DOI

10.1126/sciadv.1600835

Abstract

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 K. However, usage of the gas has been increasingly difficult because of the current worldwide shortage. Therefore, it is important to consider alternative methods of refrigeration. We show that a new type of refrigerant, the super-heavy electron metal YbCo2Zn20, 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 Yb1−xScxCo2Zn20 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 of using local magnetic moments has been applied for adiabatic demagnetization cooling. This study opens new possibilities of using itinerant magnetic moments for cryogen-free refrigeration.

Comments

This article is published as Tokiwa, Yoshifumi, Boy Piening, Hirale S. Jeevan, Sergey L. Bud’ko, Paul C. Canfield, and Philipp Gegenwart. "Super-heavy electron material as metallic refrigerant for adiabatic demagnetization cooling." Science Advances 2, no. 9 (2016): e1600835. DOI: 10.1126/sciadv.1600835. Posted with permission.

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License

Copyright Owner

The Authors

Language

en

File Format

application/pdf

Included in

Physics Commons

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