The Network Composition of Aggregate Unemployment

We develop a theory of unemployment in which workers search for jobs through a network of firms, the labor flow network (LFN). The lack of an edge between two companies indicates the impossibility of labor flows between them due to high frictions. In equilibrium, firms' hiring behavior correlates through the network, modulating labor flows and generating aggregate unemployment. This theory provides new micro-foundations for the aggregate matching function, the Beveridge curve, wage dispersion, and the employer-size premium. Using employer-employee matched records, we study the effect of the LFN topology through a new concept: `firm-specific unemployment'

Tuning Spin Hall Angles by Alloying

Within a combined experimental and theoretical study it is shown that the spin Hall angle of a substitutional alloy system can be continuously varied via its composition. For the alloy system AuxPt1-x a substantial increase of the maximum spin Hall angle compared to the pure alloy partners could be achieved this way. The experimental findings for the longitudinal charge conductivity sigma, the transverse spin Hall conductivity sigma(SH), and the spin Hall angle alpha(SH) could be confirmed by calculations based on Kubo's linear response formalism. Calculations of these response quantities for different temperatures show that the divergent behavior of sigma and sigma(SH) is rapidly suppressed with increasing temperature. As a consequence, sigma(SH) is dominated at higher temperatures by its intrinsic contribution that has only a rather weak temperature dependence