Magnetic cooling towards millikelvin temperatures using rare earth triangular magnets

Abstract

We investigate the magnetocaloric effect in the triangular lattice magnets CeMgAl11O19 and EuAl12O19, both exhibiting strong anisotropy. EuAl12O19 is a low-temperature ferro- magnet with a field-induced transition to a polarized paramagnetic state, enabling cooling to 3 He temperatures. Its high anisotropy potentially allows for rotational magnetocaloric refrigeration in fields suitable for use with permanent magnets rather than supercon- ducting magnets. CeMgAl11O19, a quantum spin liquid candidate, remains disordered at millikelvin temperatures, making it promising for ultra-low-temperature refrigeration. These properties highlight the potential of both materials for cryogenic applications - particularly for use in cooling of quantum computing devices. 1

Zkouma ́me magnetokaloricky ́ efekt v magnetech s trojuhelnı ́kovou krystalovou mr ̌ı ́z ̌ı ́ CeMgAl11O19 a EuAl12O19, ktere ́ oba vykazujı 'silnou anizotropii. EuAl12O19 je nı ́zkoteplotnı ́ feromagnet s polem indukovany ́m pr ̌echodem do polarizovane ́ho paramagneticke ́ho stavu, coz ̌ umoz ̌n ̌uje ochlazova ́nı ́ na teploty 3 He. Jeho vysoka ́ anizotropie potencia ́lne ̌ umoz ̌n ̌uje rotac ̌nı ́ magnetokaloricke ́ chlazenı ́ v magneticky ́ch polı ́ch dosaz ̌itelny ́mi pouz ̌itı ́m per- manentnı ́ch magnetu ̊, bez nutnosti supravodivy ́ch magnetu ̊. CeMgAl11O19, kandida ́t na kvantovou spinovou kapalinu, zu ̊sta ́va ́ neuspor ̌a ́dany ́ pr ̌i milikelvinovy ́ch teplota ́ch, coz ̌ z ne ̌j c ̌inı ́ slibny ́ materia ́l pro ultranı ́zkoteplotnı ́ chlazenı ́. Tyto vlastnosti zdu ̊razn ̌ujı ́ poten- cia ́l obou materia ́lu ̊ pro kryogennı ́ aplikace - zejme ́na pro pouz ̌itı ́ pr ̌i chlazenı ́ kvantovy ́ch vy ́poc ̌etnı ́ch zar ̌ı ́zenı ́. 1