Molecular spin-orbit excitations in the J_eff = 1/2 frustrated spinel GeCo$_2$O$_4$
Autor: | Tomiyasu, K., Crawford, M. K., Adroja, D. T., Manuel, P., Tominaga, A., Hara, S., Sato, H., Watanabe, T., Ikeda, S. I., Lynn, J. W., Iwasa, K., Yamada, K. |
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Rok vydání: | 2011 |
Předmět: | |
Zdroj: | Phys. Rev. B 84, 054405 (2011) |
Druh dokumentu: | Working Paper |
DOI: | 10.1103/PhysRevB.84.054405 |
Popis: | We describe powder and single-crystal inelastic neutron scattering experiments on a spinel-type antiferromagnet GeCo$_2$O$_4$, represented by an effective total angular momentum J_eff = 1/2. Several types of non-dispersive short-range magnetic excitations were discovered. The scattering intensity maps in $\vec{Q}$ space are well reproduced by dynamical structure factor analyses using molecular model Hamiltonians. The results of analyses strongly suggest that the molecular excitations below T_N arise from a hidden molecular-singlet ground state, in which ferromagnetic subunits are antiferromagnetically coupled. The quasielastic excitations above T_N are interpreted as its precursor. A combination of frustration and J_eff = 1/2 might induce these quantum phenomena. Comment: 7 pages, 4 figures, submitted to Phys. Rev. B |
Databáze: | arXiv |
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