Coexistence of Ising and XY Spin Systems on a Single Tb Atom in TbCoGa

概要

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The tetragonal compound TbCoGa<inf>5</inf>exhibits two successive magnetic transitions at T_{\text{N1}}=36.2 and T_{\text{N2}}=5.4 K. The results of the measurement of the magnetic susceptibility and specific heat indicate that the c- and ab-components of the magnetic moments of Tb<sup>3+</sup>show independent antiferromagnetic orderings at T_{\text{N1}} and T_{\text{N2}}, respectively. In this work, we have investigated the physical properties of TbCoGa<inf>5</inf>in a magnetic field. Single crystals of TbCoGa<inf>5</inf>were grown and their specific heat, electrical resistivity, magnetization and elastic constant were measured. The magnetic exchange interactions in TbCoGa<inf>5</inf>are discussed referring to the result of the magnetization process. Additionally, the present and previous results are summarized in a magnetic phase diagram. The magnetic phase diagram indicates that the behavior of T_{\text{N1}} in a changing magnetic field is similar to that of an Ising spin system, and the behavior of T_{\text{N2}} is similar to that of an XY spin system. Thus, we conclude that Ising and XY spin systems coexist on a single Tb atom in TbCoGa<inf>5</inf>.
2013-04-15