The FIR-absorption of short period quantum wires and the transition from one to two dimensions

We investigate the FIR-absorption of short period parallel quantum wires in a perpendicular quantizing magnetic field. The external time-dependent electric field is linearly polarized along the wire modulation. The mutual Coulomb interaction of the electrons is treated self-consistently in the ground state and in the absorption calculation within the Hartree approximation. We consider the effects of a metal gate grating coupler, with the same or with a different period as the wire modulation, on the absorption. The evolution of the magnetoplasmon in the nonlocal region where it is split into several Bernstein modes is discussed in the transition from: narrow to broad wires, and isolated to overlapping wires. We show that in the case of narrow and not strongly modulated wires the absorption can be directly correlated with the underlying electronic bandstructure.Comment: 15 pages, 9 figures, Revtex, to appear in Phys. Rev.

Magnetic structure and phase diagram of TmB4

Magnetic structure of single crystalline TmB4 has been studied by magnetization, magnetoresistivity and specific heat measurements. A complex phase diagram with different antiferromagnetic (AF) phases was observed below TN1 = 11.7 K. Besides the plateau at half-saturated magnetization (1/2 MS), also plateaus at 1/9, 1/8 and 1/7 of MS were observed as function of applied magnetic field B//c. From additional neutron scattering experiments on TmB4, we suppose that those plateaus arise from a stripe structure which appears to be coherent domain boundaries between AF ordered blocks of 7 or 9 lattice constants. The received results suggest that the frustration among the Tm3+ magnetic ions, which maps to a geometrically frustrated Shastry-Sutherland lattice lead to strong competition between AF and ferromagnetic (FM) order. Thus, stripe structures in intermediate field appear to be the best way to minimize the magnetostatic energy against other magnetic interactions between the Tm ions combined with very strong Ising anisotropy.Comment: 4 pages, 4 figures, conference contribution - CSMAG 0

Contingent Capital with Sequential Triggers

Contingent capital has great potential to help make systemically important financial institutions (SIFIs) safer, minimize systemic risk, and help avoid another financial crisis. United States policymakers may not have fully utilized the potential of contingent capital. A draft by the European Union (EU) Commission already suggests the mandatory issuance of contingent capital securities in the resolution phase of systemically important banks in Europe. The Dodd-Frank Wall Street Reform and Consumer Protection Act mandates a study on the feasibility of contingent capital. This Article proposes the use of contingent capital with a sequential trigger as an early preventative tool and as a reorganization tool before liquidation, independent of protection under bankruptcy proceedings. The first preventative trigger, in a going concern conversion, would convert a fixed amount of debt to equity at a stage when the institution is still sound on a micro prudential basis but shows early signs of substantial weakening. The first trigger in this proposal would help prevent an externality on taxpayers. The second reorganization trigger would increase voting rights for holders of contingent capital after conversion to equity at the reorganization stage. Sequential triggers could incentivize corrective action by SIFI management. The second trigger, gone concern conversion, introduces a quasi-preparation stage for bankruptcy, independent of management decisions or corrective action by regulators. The second trigger would only be utilized if evidence proves that the first conversion did not internalize the costs of bank failure through the equity conversion induced capital increase. The second trigger could be used either to prevent a SIFI resolution or to assist in a SIFI?s resolution or bankruptcy. The proposal would work seamlessly with the regulatory framework proposed by the EU Commission and could provide U.S. policymakers with a new perspective on the multiple uses of contingent capital in the context of bank restructuring

Contingent Capital in European Union Bank Restructuring

The uncoordinated reorganization and resolution of Systemically Important Financial Institutions in different countries pose many challenges. Contingent capital provides a viable alternative for the efficient restructuring and resolution of failing financial institutions. Contingent Capital provides a mechanism for internalizing banks’ failure costs and helps return distressed financial institutions to solvency. This article offers a comparative perspective on bank resolution and restructuring in the European Union, Switzerland, the United Kingdom and Germany and shows that Contingent Capital could play a substantial role in bank restructuring