Quadrupolar effect and rattling motion in heavy fermion superconductor PrOs_4Sb_{12}

The elastic properties of a filled skutterudite PrOs_4Sb_{12} with a heavy Fermion superconductivity at T_C=1.85 K have been investigated. The elastic softening of (C_{11}-C_{12})/2 and C_{44} with lowering temperature down to T_C indicates that the quadrupolar fluctuation due to the CEF state plays a role for the Cooper paring in superconducting phase of PrOs_4Sb_{12}. A Debye-type dispersion in the elastic constants around 30 K revealed a thermally activated Gamma_{23} rattling due to the off-center Pr-atom motion obeying tau=tau_{0}exp(E/k_{B}T) with an attempt time tau_0=8.8*10^{-11} sec and an activation energy E=168 K. It is remarkable that the charge fluctuation of the off-center motion with Gamma_{23} symmetry may mix with the quadrupolar fluctuation and enhance the elastic softening of (C_{11}-C_{12})/2 just above T_C.Comment: 5 pages, 4 figures, to be published to Phys. Rev.

Current Status of Firm-Bank Relationships and the Use of Collateral in Japan: An Overview of the Teikoku Databank Data

April 8, 2011December 2010This is a study from the research group for the Program for Promoting Social Science Research Aimed at Solutions of Near-Future Problems “Design of Interfirm Network to Achieve Sustainable Economic Growth.”近未来の課題解決を目指した実証的社会科学推進事業42 p

Current Status of Interfirm Relationships in Japan: An Overview of the Teikoku Databank Data

December 2010近未来の課題解決を目指した実証的社会科学推進事業69 p

Measuring the Systemic Risk in Interfrm Transaction Networks (Forthcoming in Journal of Economic Behavior and Organization) Program for Promoting Social Science Research Aimed at Solutions of Near-Future Problems Design of Interfirm Network to Achieve Sus

Abstract Using a unique and massive data set that contains information on interfirm transaction relationships, this study examines default propagation in trade credit networks and provides direct and systematic evidence of the existence and relevance of such default propagation. Not only do we implement simulations in order to detect prospective defaulters, we also estimate the probabilities of actual firm bankruptcies and compare the predicted defaults and actual defaults. We find, first, that an economically sizable number of firms are predicted to fail when their customers default on their trade debt. Second, these prospective defaulters are indeed more likely to go bankrupt than other firms. Third, firms that have abundant external sources of financing or whose transaction partners have such abundant sources are less likely to go bankrupt even when they are predicted to default. This provides evidence for the existence and relevance of firms -called "deep pockets" by Kiyotaki and Moore (1997) -that can act as shock absorbers