Measurements of the heat capacity of two single crystals of ErRh4B4 have been made in the temperature range of 0.4 to 1.3 K. The calorimeter utilized inn this investigation allows the heat capacity to be determined with the sample temperature either monotonically increasing or decreasing. The data do not indicate the presence of a latent heat in the measurements made while cooling the sample. By performing an integration of the specific heat, determined from the decreasing temperature data, a value for the entropy of the magnetic system is calculated. This value is consistent with the entropy anticipated for the lowest crystal field energy levels of Er to be two doublets.
Bibliographical noteFunding Information:
This work was funded in part by the Graduate School of the University of Minnesotaa nd the Research Corporation. One of the authors (EDD) gratefully acknowledgesre ceipt of an A.P. Sloan Fellowship. The authorsw ould also like to thank Dr. S. Lambert, Prof. B. Maple, Prof. W. ZimmermannD,r . G. Crabtreea ndDr. B. Dunlap for numerousc onversations.