科研之友
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摘要
We report a study of the thermal conductivity. of the spin-ice material Dy2Ti2O7. From the anisotropic magnetic-field dependence of. and by additional measurements on the phononic reference compounds Y2Ti2O7 and (Dy0.5Y0.5)(2)Ti2O7, we are able to separate the phononic and the magnetic contributions to the total heat transport, i.e., kappa(ph) and kappa(mag), respectively, which both depend on the magnetic field. The field dependence of kappa(ph) arises from the noncollinear magnetic moments of the Dy ions, which tend to align along the field direction. For kappa(mag), we observe a highly anisotropic magnetic-field dependence, which correlates with the corresponding magnetization data reflecting the different magnetic-field induced spin-ice ground states. The magnitude of kappa(mag) increases with the degree of the ground-state degeneracy. This anisotropic field dependence as well as various hysteresis effects suggest that kappa(mag) is essentially determined by the mobility of the magnetic monopole excitations in spin ice.
- 出版日期2013-8-9
