2003/08/31 by Marco Frasca
Physics and Astronomy · #cond-mat.mes-hall #cond-mat.str-el #hep-th #quant-ph
paper · pdf · doi:10.1103/physrevb.68.193413
published as Phys.Rev. B68 (2003) 193413 · 10 pages, no figure. Changed title. Revised version accepted for publication in Physical Review B
arxiv created 2003/10/07 · arxiv updated 2009/12/01
We consider an exchange model of itinerant electrons in a Heisenberg ferromagnet and we assume that the ferromagnet is in a fully polarized state. Using the Holstein-Primakoff transformation we are able to obtain a boson-fermion Hamiltonian that is well-known in the interaction between light and matter. This model describes the spontaneous emission in two-level atoms that is the proper decoherence mechanism when the number of modes of the radiation field is taken increasingly large, the vacuum acting as a reservoir. In the same way one can see that the interaction between the bosonic modes of spin waves and an itinerant electron produces decoherence by spin flipping with a rate proportional to the size of the system. In this way we are able to show that the experiments on quantum dots, described in D. K. Ferry et al. [Phys. Rev. Lett. \bf 82, 4687 (1999)], and nanowires, described in D. Natelson et al. [Phys. Rev. Lett. \bf 86, 1821 (2001)], can be understood as the interaction of itinerant electrons and an electron gas in a fully polarized state.