Fragility inp-spin models

Opto-spintronics in InP using ferromagnetic tunnel spin filters

Wedemonstrate opto-spintronics using Fe-doped IndiumPhosphide (InP). Themethod is based on optical orientation of InP conduction electron spinswhich are electrically detected in planar InP/ oxide/Ni tunnel spinfilters.We separate the optical excitation from electrical detection, avoiding thus additional interactions of photonswith the ferromagnet. Interface engineering provides a surface iron a...

Spin Lifetime in Electron-Doped InP Quantum Dots

Spin relaxation of electrons doped in InP quantum dots was studied by means of luminescence pump-probe and Hanle measurements. Optical pumping makes spins of doped electrons to be oriented in parallel to the helicity of the circularly polarized excitation. The luminescence pump-probe showed the spin orientation of the doped electrons decay on a millisecond time-scale. Hanle measurement clarifie...

Fragility of Purely Real Macroeconomic Models

Over the past thirty years, a great deal of business cycle research has been based on purely real models that abstract from the presence of nominal rigidities, and so (at least implicitly) assume that the Phillips curve is vertical. In this paper, I show that such models are fragile, in the sense that their implications change significantly when the Phillips curve is even slightly less than ver...

Spin Foam Models

While the use of spin networks has greatly improved our understanding of the kinematical aspects of quantum gravity, the dynamical aspects remain obscure. To address this problem, we deene the concept of a `spin foam' going from one spin network to another. Just as a spin network is a graph with edges labeled by representations and vertices labeled by intertwining operators, a spin foam is a 2-...

Classical Spin Models