Abstract
We present magnetization () data of the -metal alloy at vanadium concentrations close to where the onset of long-range ferromagnetic (FM) order is suppressed to zero temperature. Above , the temperature () and magnetic field () dependencies of the magnetization are best described by simple nonuniversal power laws. The exponents of and are related by for wide temperature () and field () ranges. is strongly dependent, decreasing from 1 at to for . This behavior is not compatible with either classical or quantum critical behavior in a clean 3D FM. Instead it closely follows the predictions for a quantum Griffiths phase associated with a quantum phase transition in a disordered metal. Deviations at the lowest temperatures hint at a freezing of large clusters and the onset of a cluster glass phase.
- Received 18 September 2009
DOI:https://doi.org/10.1103/PhysRevLett.104.066402
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