Breakdown of Landau-Ginzburg-Wilson theory for certain quantum phase transitions

T. Vojta; D. Belitz; R. Narayanan; T. R. Kirkpatrick

doi:doi:10.1209/epl/i1996-00208-x

Breakdown of Landau-Ginzburg-Wilson theory for certain quantum phase transitions DOI: 10.1209/epl/i1996-00208-x

Europhys. Lett, 36 (3), pp. 191-196 (1996)

Breakdown of Landau-Ginzburg-Wilson theory for certain quantum phase transitions

T. Vojta , D. Belitz , R. Narayanan and T. R. Kirkpatrick

Department of Physics and Materials Science Institute, University of Oregon, Eugene, OR 97403, USA
Institute for Physical Science and Technology, and Department of Physics, University of Maryland - College Park, MD 20742, USA

(received 10 June 1996; accepted in final form 10 September 1996)

PACS. 64.60Ak - Renormalization-group, fractal, and percolation studies of phase transitions.
PACS. 75.10Jm - Quantized spin models.
PACS. 75.40 - Critical-point effects, specific heats, short-range order.

Abstract:

The quantum ferromagnetic transition of itinerant electrons is considered. It is shown that the Landau-Ginzburg-Wilson theory described by Hertz and others breaks down due to a singular coupling between fluctuations of the conserved order parameter. This coupling induces an effective long-range interaction between the spins of the form

. It leads to unusual scaling behavior at the quantum critical point in

dimensions, which is determined exactly.