The description of solids at a microscopic level is complex, involving the interaction of a
huge number of its constituents, such as ions or electrons. It is impossible to solve the …

We compute the phase diagram of the one-dimensional Bose-Hubbard model with a
quasiperiodic potential by means of the density-matrix renormalization group technique …

In this paper we continue and extend a systematic study of plateaux in magnetization curves
of antiferromagnetic Heisenberg spin-1/2 ladders. We first review a bosonic field-theoretical …

The natural mineral azurite Cu 3 (CO 3) 2 (OH) 2 is a frustrated magnet displaying unusual
and controversially discussed magnetic behavior. Motivated by the lack of a unified …

An external magnetic field induces large relative changes in the entropy of one-dimensional
quantum spin systems at finite temperatures. This leads to a magnetocaloric effect, ie a …

We study inhomogeneous quantum quenches in the attractive regime of the sine-Gordon
model. In our protocol, the system is prepared in an inhomogeneous initial state in finite …

We study the field dependence of the antiferromagnetic spin-1 2 Heisenberg model on the
square lattice by means of exact diagonalizations. In the first part, we calculate the spin …

Plateaux in the magnetization curves of the square-, triangular-and hexagonal-lattice spin-
1/2 XXZ antiferromagnet are investigated. One finds a zero-magnetization plateau …

We analyze the infrared asymptotic properties of two chains coupled by one-electron
tunneling, when electron interactions are restricted to a small momentum transfer. We study …

We present a review of different field theory techniques that have proved very useful in the
study of quantum magnets in low dimensions We first review the application of the spin …