Publication Date:
2011-04-19
Description:
Author(s): L. J. Chang, W. Schweika, Y. -J. Kao, Y. Z. Chou, J. Perßon, Th. Brückel, H. C. Yang, Y. Y. Chen, and J. S. Gardner Polycrystalline samples of Ho_{x} Tb_{2-x} Ti_{2} O_{7} (0 〈 x 〈 2) have been prepared and characterized for their structural and magnetic properties. The parent compounds of this solid solution are the spin ice Ho_{2} Ti_{2} O_{7} and the spin liquid Tb_{2} Ti_{2} O_{7} . Specific-heat measurements on HoTbTi_{2} O_{7} (x = 1.0) reveal the absence of a long-range order state above 0.5 K. The integrated entropies of all Ho_{x} Tb_{2-x} Ti_{2} O_{7} specimens up to 30 K scale well with the ratio of spin ice and spin liquid in the composition. The neutron diffraction spectrum of HoTbTi_{2} O_{7} exhibits a dipolar spin-ice pattern and can be well described by mean-field theory for 〈111〉 Ising spins, nearest-neighbor exchange, and dipolar interactions. Inelastic neutron scattering on HoTbTi_{2} O_{7} reveals two dispersionless excitations, one of ∼2.5 meV out of the ground state, and a 4-meV transition out of an excited state. We argue that these data suggest that the very strong single-ion effects of Ho_{2} Ti_{2} O_{7} and Tb_{2} Ti_{2} O_{7} persist in the Ho_{x} Tb_{2-x} Ti_{2} O_{7} (0
Keywords:
Magnetism
Print ISSN:
1098-0121
Electronic ISSN:
1095-3795
Topics:
Physics
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