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Hotta, Takashi
Physica B; Condensed Matter, 378-380, p.51 - 53, 2006/05
Times Cited Count：4 Percentile：22.76(Physics, Condensed Matter)In order to clarify what types of spin and orbital fluctuations dominate over low-temperature electronic properties of Pr-based filled skutterudites, we evaluate multipole susceptibility based on a multiorbital Anderson model constructed from a 
- coupling scheme. It is found that magnetic and quadrupole fluctuations are dominant at low temperatures. When we further include the effect of rattling as dynamical Jahn-Teller phonons, there remain quadrupole and octupole fluctuations, which may induce exotic superconducting pairing.
Hotta, Takashi
Journal of the Physical Society of Japan, 74(9), p.2425 - 2429, 2005/09
Times Cited Count：26 Percentile：73.62(Physics, Multidisciplinary)In order to clarify exotic multipole properties of filled skutterudites, we evaluate multipole susceptibility for 
=1
5, where is the local 
-electron number, on the basis of a multiorbital Anderson model constructed using the - coupling scheme. For =1, magnetic fluctuations dominate over low-temperature electronic properties, while for =2 and 4, electronic states are dominated by both magnetic and quadrupole fluctuations. For =3 and 5, octupole fluctuations are found to be significant, depending on the crystalline electric field potential. We discuss possible relevance of the results to actual materials.
-electron systems with filled skutterudite structureHotta, Takashi
Journal of the Physical Society of Japan, 74(4), p.1275 - 1288, 2005/04
Times Cited Count：25 Percentile：72.91(Physics, Multidisciplinary)In order to understand electronic properties of filled skutterudite materials, the Anderson model is analyzed by using the numerical renormalization group method to evaluate magnetic susceptibility and entropy of electron for each case of =113, where is the number of electrons per rare-earth ion. For the 
-electron system corresponding to the Pr-based filled skutterudite, it is found that magnetic fluctuations significantly remain at low temperatures, even when the ground state is 
singlet, if 
triplet is the excited state with small excitation energy. By analyzing an orbital degenerate Hubbard model constructed based on the - coupling scheme, we find that anisotropic Cooper-pair mediated by magnetic fluctuations appears in a limited region in which the singlet and triplet ground states are interchanged.
-electron systemsHotta, Takashi
Physica B; Condensed Matter, 359-361, p.1003 - 1005, 2005/04
Times Cited Count：1 Percentile：6.23(Physics, Condensed Matter)In order to understand magnetic properties of filled skutterudite materials, we evaluate magnetic susceptibility of the Anderson model with orbital degeneracy by using the numerical renormalization group method. Even when the local ground state is , magnetic fluctuations significantly remain, if is the excited state with small excitation energy, as experimentally proposed for Pr-based filled skutterudite compounds.
Hotta, Takashi
Physical Review Letters, 94(6), p.067003_1 - 067003_4, 2005/02
Times Cited Count：15 Percentile：62.72(Physics, Multidisciplinary)In order to clarify magnetic properties of filled skutterudites, we analyze the Anderson model including seven orbitals hybridized with an 
conduction band using a numerical technique. For =2 corresponding to Pr-based filled skutterudites, where is the local -electron number, even if the ground state is a singlet, there remain significant magnetic fluctuations from a triplet state with a small excitation energy. This result can be understood by the fact that -electron states are clearly distinguished as itinerant and localized ones in the filled skutterudite structure. This picture also explains the complex results for -electron magnetic susceptibility and entropy for =113.
