Low-Temperature Magnetic Orderings and Fermi Surface Properties of LaCd11, CeCd11, and PrCd11 with a Caged Crystal Structure

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We succeeded in growing single crystals of cage-structure compounds RCd11 (R: La, Ce, and Pr) and precisely studied their low-temperature magnetic and electronic properties by measuring electrical resistivity, magnetic susceptibility, magnetization, specific heat, and the de Haas–van Alphen (dHvA) effect. We found antiferromagnetic ordering at 0.44 and 0.39 K in CeCd11 and PrCd11, respectively, and clarified the magnetic phase diagrams of the compounds. In addition, low-lying crystalline electric field (CEF) schemes were proposed from the specific heat results of both compounds. From the present study, the antiferromagnetic ordering in PrCd11 is found to be of the exchange-induced type with a singlet ground state. From the dHvA experiment, we detected small dHvA branches ranging from $7\times 10^{5}$ to $2\times 10^{7}$ Oe, which correspond to small Fermi surfaces. This is mainly due to a small Brillouin zone based on a large unit cell. Moreover, the dHvA frequencies and cyclotron masses are approximately the same among RCd11, revealing a localized character of 4f electrons in CeCd11 and PrCd11.
2010-04-15