Publications de Tommaso Coletta

Semiclassical theory of the magnetization process of the triangular lattice Heisenberg model

Frédéric Mila, Karlo Penc, Tommaso Coletta, Tamás András Tóth

Motivated by the numerous examples of 1/3 magnetization plateaux in the triangular-lattice Heisenberg antiferromagnet with spins ranging from 1/2 to 5/2, we revisit the semiclassical calculation of the magnetization curve of that model, with the aim of com ...

2016

Dynamical structure factors and excitation modes of the bilayer Heisenberg model

Frédéric Mila, Tommaso Coletta

Using quantum Monte Carlo simulations along with higher-order spin-wave theory, bond-operator and strong-coupling expansions, we analyze the dynamical spin structure factor of the spin-half Heisenberg model on the square-lattice bilayer. We identify distin ...

2015

Semiclassical evidence of columnar order in the fully frustrated transverse-field Ising model on the square lattice

Frédéric Mila, Tommaso Coletta

We investigate the zero-temperature phase diagram of the fully frustrated transverse-field Ising model on the square lattice both in the classical limit and in the presence of quantum fluctuations. At the classical level (the limit of infinite spin S), we ...

2014

Unconventional mechanisms of magnetic ordering in frustrated models of quantum magnetism

Tommaso Coletta

In this thesis we investigate in the semiclassical approximation how unconventional magnetic ordering, that is magnetic ordering which is not predicted at the classical level, emerges in a variety of frustrated models of quantum magnetism. The first part o ...

EPFL2013

Quantum stabilization of classically unstable plateau structures

Frédéric Mila, Tommaso Coletta

Motivated by an intriguing report, in some frustrated quantum antiferromagnets, of magnetization plateaus whose simple collinear structure is not stabilized by an external magnetic field in the classical limit, we develop a semiclassical method to estimate ...

2013

Semiclassical approach to ground-state properties of hard-core bosons in two dimensions

Frédéric Mila, Tommaso Coletta, Nicolas Laflorencie

Motivated by some inconsistencies in the way quantum fluctuations are included beyond the classical treatment of hard-core bosons on a lattice in the recent literature, we revisit the large-S semiclassical approach to hard-core bosons on the square lattice ...

2012

Evidence for Columnar Order in the Fully Frustrated Transverse Field Ising Model on the Square Lattice

Frédéric Mila, Tommaso Coletta, Sandro Wenzel

Using extensive classical and quantum Monte Carlo simulations, we investigate the ground-state phase diagram of the fully frustrated transverse field Ising model on the square lattice. We show that pure columnar order develops in the low-field phase above ...

2012

Phase diagram of the fully frustrated transverse-field Ising model on the honeycomb lattice

Frédéric Mila, Jean-David Picon, Tommaso Coletta

Motivated by the current interest in the quantum dimer model on the triangular lattice, we investigate the phase diagram of the closely related fully frustrated transverse-field Ising model on the honeycomb lattice using classical and semiclassical approxi ...

2011

Frustration- induced plateaus in S >= 1/2 Heisenberg spin ladders

Frédéric Mila, Jean-David Picon, Salvatore Manmana, Tommaso Coletta, Frédéric Alexis Michaud

We study the T=0 magnetization of frustrated two-leg spin ladders with arbitrary value of the spin S. In the strong-rung limit, we use degenerate perturbation theory to prove that frustration leads to magnetization plateaus at fractional values of the magn ...

2010