摘要
Magnetocaloric material is the key working substance for magnetic refrigerant technology,for which the low-field and low-temperature magnetocaloric effect(MCE)performance is of great importance for practical applications at low temperatures.Here,a giant low-field magnetocaloric effect in ferromagnetically ordered Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds was reported,and the magnetic structure was characterized based on low-temperature neutron powder diffraction.With increasing Tm content from 0 to 1,the Curie temperature of Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds decreases from 16.0 K to 3.6 K.For Er_(0.7)Tm_(0.3)Al_(2) compound,it showed the largest low-field magnetic entropy change(–SM)with the peak value of 17.2 and 25.7 J/(kg K)for 0–1 T and 0–2 T,respectively.The(–SM)max up to 17.2 J/(kg K)of Er0.7Tm0.3Al2 compound for 0–1 T is the largest among the intermetallic magnetocaloric materials ever reported at temperatures below 20 K.The peak value of adiabatic temperature change(Tad)max was determined as 4.13 K and 6.87 K for 0–1 T and 0–2 T,respectively.The characteristic of second-order magnetic transitions was confirmed on basis of Arrott plots,the quantitative criterion of exponent n,rescaled universal curves,and the mean-field theory criterion.The outstanding low-field MCE performance with low working temperatures indicates that Er_(1-x)Tm_(x)Al_(2)(0≤x≤1)compounds are promising candidates for magnetic cooling materials at liquid hydrogen and liquid helium temperatures.
基金
supported by the National Key Research and Development Program of China(Nos.2021YFB3501202 and 2019YFB2005800)
the Science Center of the National Science Foundation of China(No.52088101)
the National Natural Science Foundation of China(Nos.51871019,52171170,52130103,51961145305,51971026,and 52171169)
the Beijing Natural Science Foundation Key Program(Grant Nos.Z190007 and Z200007),and“111 Project”(No.B170003).
