Dy₃Ga₅O₁₂ガーネット単結晶の極低温熱スイッチ特性

抄録

Thermal conductivity of Dy₃Ga₅O₁₂ garnet single crystal has been measured between 2 and 20K with various magnetic fields between 0 and 5T. We have found a large magnetic field dependence of the thermal conductivity (λ); λ decreases with the magnetic field from 0 to 1T and then increases slightly above 1.5T. The maximum reduction in λ is found at 3.5K and 1.5T. The value is -70 times smaller than that at 3.5K and 0T. The experimental result shows that Dy₃Ga₅O₁₂ single crystal has the thermal switch function controlled by the magnetic field between 0 and 1.5T in the temperature between 2 and 10K. The large magnetic field dependence of λ can be explained by the resonant type phonon scattering corresponding to the phonon-induced transition between the energy levels of rate earth ions which are modified by the magnetic field.