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TT: Tiefe Temperaturen
TT 14: Postersitzung II: Korrelierte Systeme(1-40), Theorie der Supraleitung(41-50), Metall-Isolator-Übergang, Lokalisierung(51-66), Niederdimensionale Systeme, Quantenhalleffekt(67-80), Pinning, kritische Ströme und Vortexdynamik(81-93), HTSL-Drähte und -Bänder(94-98), Massive HTSL(99-104), supraleitende Borkarbide(105-109)
TT 14.37: Poster
Mittwoch, 19. März 1997, 15:00–18:30, Z1
The ferromagnetic quantum phase transition of itinerant electrons — •Thomas Vojta1, Dietrich Belitz2, and Theodore R. Kirkpatrick3 — 1Institut für Physik, Technische Universität, D-09107 Chemnitz — 2Department of Physics, University of Oregon, Eugene, OR 97403 — 3Department of Physics, University of Maryland, College Park, MD 20742
We consider the quantum ferromagnetic transition at zero temperature in clean itinerant electron systems. We find that the Landau-Ginzburg-Wilson order parameter field theory breaks down since the electron-electron interaction leads to singular coupling constants in the Landau-Ginzburg-Wilson functional. These couplings generate an effective long-range interaction between the spin or order parameter fluctuations of the form 1/r2d−1, with d the spatial dimension. This leads to unusual scaling behavior at the quantum critical point in 1<d≤ 3, which we determine exactly. We also discuss the quantum-to-classical crossover at small but finite temperatures, which is characterized by the appearance of multiple temperature scales. A comparison with recent results on disordered itinerant ferromagnets is given.