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

TitleSuper-heavy electron material as metallic refrigerant for adiabatic demagnetization cooling
Publication TypeJournal Article
Year of Publication2016
AuthorsTokiwa, Y, Piening, B, Jeevan, HS, Bud'ko, SL, Canfield, PC, Gegenwart, P
JournalScience Advances
Date Published09
Type of ArticleArticle
ISBN Number2375-2548
Accession NumberWOS:000383734400018
Keywordsphysics, quantum-critical-point, Technology - Other Topics

Low-temperature refrigeration is of crucial importance in fundamental research of condensedmatter 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 He-3 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 Yb(1-x)ScxCo(2)Zn(20) by partial Sc substitution, with x similar to 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.

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Short TitleSci. Adv.
Alternate JournalSci. Adv.