This review discusses instabilities of the Fermi-liquid state of conduction electrons in metals
with particular emphasis on magnetic quantum critical points. Both existing theoretical …

It is now widely accepted that the cuprate superconductors are characterized by a long-
range order similar to that present in the Bardeen-Cooper-Schrieffer (BCS) theory, that …

The theory of second-order phase transitions is one of the foundations of modern statistical
mechanics and condensed-matter theory. A central concept is the observable order …

We present the critical theory of a number of zero-temperature phase transitions of quantum
antiferromagnets and interacting boson systems in two dimensions. The most important …

Abstract We study the S= 1/2 Heisenberg antiferromagnet on the pyrochlore lattice in the
limit of strong easy-axis exchange anisotropy. We find, using only standard techniques of …

Using ground-state projector quantum Monte Carlo simulations in the valence-bond basis, it
is demonstrated that nonfrustrating four-spin interactions can destroy the Néel order of the …

We study the effect of hedgehog suppression in the O (3) sigma model in D= 2+ 1. We show
via Monte Carlo simulations that the sigma model can be disordered while effectively …

The antiferromagnetic to valence-bond-solid phase transition in the two-dimensional JQ
model (an S= 1/2 Heisenberg model with four-spin interactions) is studied using large-scale …

The observation of a separation between the antiferromagnetic phase boundary and the
small-large Fermi surface transition in recent experiments has led to the proposal that …

The quantum spin-1∕ 2 antiferromagnetic Heisenberg model on a two dimensional
triangular lattice geometry with spatial anisotropy is relevant to describe materials such as …