Publications de Frédéric Alexis Michaud

Exact Ground States of Frustrated Spin-1 Ising-Heisenberg and Heisenberg Ladders in a Magnetic Field

Ground states of the frustrated spin-1 Ising-Heisenberg two-leg ladder with Heisenberg intra-rung coupling and only Ising interaction along legs and diagonals are rigorously found by taking advantage of local conservation of the total spin on each rung. Th ...

Polish Acad Sciences Inst Physics2014

Realization of higher Wess-Zumino-Witten models in spin chains

Frédéric Mila, Frédéric Alexis Michaud, Salvatore Manmana

Building on the generalization of the exactly dimerized Majumdar-Ghosh ground state to arbitrary spin S for the Heisenberg chain with a three-site term (Si-1 . S-i)(S-i . Si+1) + H.c., we use density-matrix renormalization group simulations and exact diago ...

2013

Phase diagram of the spin-1 Heisenberg model with three-site interactions on the square lattice

Frédéric Mila, Frédéric Alexis Michaud

We study the spin S = 1 antiferromagnetic Heisenberg model on the square lattice with, in addition to the nearest-neighbor interaction, a three-site interaction of the form (S-i . S-j)(S-j . S-k) + H.c. This interaction appears naturally in a strong coupli ...

2013

Intermediate magnetization plateaus in the spin-1/2 Ising-Heisenberg and Heisenberg models on two-dimensional triangulated lattices

Frédéric Mila, Frédéric Alexis Michaud, Jana Cisárová

The ground state and zero-temperature magnetization process of the spin-1/2 Ising-Heisenberg model on two-dimensional triangles-in-triangles lattices are exactly calculated using eigenstates of the smallest commuting spin clusters. Our ground-state analysi ...

2013

Emergence and Detection of Exotic Phases in Spin-1 Systems

Frédéric Alexis Michaud

This work is devoted to the study of spin S = 1 systems, and more precisely to the emergence of exotic quantum phases in such systems, and to the establishment of tools to observe such phases. It is split in four main chapters. In the first chapter, we sho ...

EPFL2013

Berry phase investigation of spin-S ladders

Frédéric Mila, Frédéric Alexis Michaud, Natalia Chepiga

We investigate the properties of antiferromagnetic spin-S ladders with the help of local Berry phases defined by imposing a twist on one or a few local bonds. In gapped systems with time-reversal symmetry, these Berry phases are quantized, hence able in pr ...

2013

Antiferromagnetic Spin-S Chains with Exactly Dimerized Ground States

Frédéric Mila, Frédéric Alexis Michaud, François Vernay, Salvatore Manmana

We show that spin S Heisenberg spin chains with an additional three-body interaction of the form (Si-1 center dot S-i)(S-i center dot S-i (+) (1)) + H.c. possess fully dimerized ground states if the ratio of the three-body interaction to the bilinear one i ...

2012

Theory of inelastic light scattering in spin-1 systems: Resonant regimes and detection of quadrupolar order

Frédéric Mila, Frédéric Alexis Michaud, François Vernay

Motivated by the lack of an obvious spectroscopic probe to investigate nonconventional order such as quadrupolar orders in spin S > 1/2 systems, we present a theoretical approach to inelastic light scattering for spin-1 quantum magnets in the context of a ...

2011

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

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

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