Infinite-randomness critical point in the itinerant quantum antiferromagnet

Abstract

We study the quantum phase transition in the three-dimensional disordered itinerant antiferromagnet by Monte-Carlo simulations of the order-parameter field theory. We find strong evidence for the transition being controlled by an infinite-randomness fixed point: The dynamical scaling is activated, i.e., the logarithm of the energy scales like a power of the length, implying a dynamical exponent of infinity. The probability distribution of the energy gaps is very broad and becomes broader with increasing system size, even on a logarithmic scale.