Development and application of rare earth intermetallic compounds to working substances for extremely low-temperature refrigerator of small size

1 Magnetic susceptibilities are measured for the rare earth intermetallic compounds of ErAg， HoAu_2， ErAu_2 and Er_2 Au。作为HoAu_2和Er_2Au的化合物，它发现了温度依赖性的问题，使其比以前发现的其他异常现象更严重。这些异常现象可以推断出这些化合物中新的磁序转换的存在。2除了Er_2Au之外，这些化合物的特殊热度在2和30 K之间测量。ErAg：母亲的异常现象在一个温度就在诺埃尔温度（T_N）以下发现，在那里，可疑现象是不可观测的。peak value of specific heat is obtained to be about 20 J·K^\-1>·mol^\-3\（0.7 J·K^\-1>·cm^\-3\） at T_N。HoAu_2 ：特定热浪中的峰值可以在温度上观察到新的异常现象，在可疑性上被发现。specific heat T_N has a peak value of 10 J·K^\-1>·mol^\-3\（0.27 J·K^\-1>·cm^\-3\）。ErAu_2 ：T_N特定热度的最大值为13 J·K^<-1>·mol^ ... More <-3> （0.36 J·K^<-1>·cm^<-3>）。Er_2Au ：T_N每单位体积的特定热量的跳跃被粗略估计为在分子场近似的基础上超过1.5次ErAg、HoAu_2和ErAu_2每单位体积以下的10 K被发现低于他的气体作为一个低温度反射器的工作物质，它发现了每单位化合物的特定热量体积在温度以下10 K高于通常用于再生器的17 K（在ErAg的情况下）。因此，这可能是有可能从这些化合物和铅的复合材料中制造再生器，所以他将主要在这些化合物以下10 K以下的废气热量，在这些化合物以上10 K主要在铅。由于Er_2Au的化合物，每单位体积的特定热量跳跃，估计在8 K时的特定热量峰值值超过其一半，预计在相同的温度范围内（T_N =6.2 K）。Less（低）

1 Magnetic susceptibilities are measured for the rare earth intermetallic compounds of ErAg, HoAu_2, ErAu_2 and Er_2Au. As for the compounds of HoAu_2 and Er_2Au, it is found that temperature dependence of the susceptibilities make anomalies other than those found previously. These anomalies suggest the existence of new magnetic order-order transitions in these compounds.2 Specific heats of these compounds except for Er_2Au are measured between 2 and 30 K.ErAg : Mother anomaly is found at a temperature just below the Noel temperature (T_N), where the susceptibility anomaly is not observed. The peak value of specific heat is obtained to be about 20 J・K^<-1>・mol^<-3> (0.7 J・K^<-1>・cm^<-3>) at T_N. HoAu_2 : A peak in the specific heat is observed at the temperature where the new anomaly is found in susceptibility mentioned above. The specific heat at T_N has a peak value of 10 J・K^<-1>・mol^<-3> (0.27 J・K^<-1>・cm^<-3>). ErAu_2 : The maximum value of specific heat at T_N is 13 J・K^<-1>・mol^ … More <-3> (0.36 J・K^<-1>・cm^<-3>). Er_2Au : A jump of specific heat per unit volume at T_N is roughly estimated to be about 1.5 times of that of ErAg on the basis of molecular field approximation.3 The specific heats of ErAg, HoAu_2 and ErAu_2 per unit volume below 10 K are found to be lower than that of He gas which is used as a working substance of low-temperature refrigerator, It is found that the specific heats per unit volume of the compounds at temperatures below 10 K are higher than that of lead used generally for a regenerator (below 17 K in the case of ErAg). Therefore, it may be probable to make a regenerator from composite materials of these compounds and lead, so as to discharge heat of He gas below 10 K mainly to these compounds and above 10 K mainly to lead. As for the compound Er_2Au, a jump of specific heat per unit volume, which is estimated to be more than a half of the peak value of the specific heat of He gas at about 8 K, is expected around the same temperature range (T_N=6.2 K). Less