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Anisotropic Cooperative Jahn-Teller Effect and Metamagnetism in P r C u 2

1998; Physical Society of Japan; Volume: 67; Issue: 2 Linguagem: Inglês

10.1143/jpsj.67.636

1347-4073

Rikio Settai, Shingo Araki, Parhat Ahmet, Melike Abliz, Kiyohiro Sugiyama, Yoshichika Ōnuki, Terutaka Gotô, Hiroyuki Mitamura, Tsuneaki Goto, Shigeru Takayanagi,

Magnetic Properties of Alloys

We have studied the origin of the cooperative Jahn-Teller effect and the metamagnetic transition in the orthorhombic compound PrCu 2 . We have determined the anisotropic ferroquadrupole phase diagram by measuring the specific heat and thermal expansion under magnetic fields. With increasing the field, the Jahn-Teller transition temperature increases slightly for the field along a - and c -axes, while it decreases intensively along the b -axis. The phase diagram can be explained quantitatively by including the quadrupolar interaction of - K JT < O x y > O x y in the crystalline electric field and Zeeman Hamiltonian. The metamagnetic transition, which brings about the conversion between the easy ( a )- and hard ( c )-axes magnetization, has been also studied through the magnetostriction. This phenomenon is also explained quantitatively on the basis of the quadrupolar interaction of - K M < O 2 2 > O 2 2 . The sign of < O 2 2 > is found to be negative in the state where the c -axis is the hard one, while it changes from negative to positive above the metamagnetic transition field.