In the physics of the fractional quantum Hall (FQH) effect, a zoo of Abelian topological
phases can be obtained by varying the magnetic field. Aiming to reach the same …

We systematically study the effects of higher-order interactions on the S= 3 2, 1 orthogonal
dimer chains using exact diagonalization and density matrix renormalization group. Due to …

We study the Néel to fourfold columnar valence bond solid (cVBS) quantum phase transition
in a sign-free S= 1 square-lattice model. This is the same kind of transition that for S= 1/2 has …

We introduce a strategy to write down lattice models of spin rotational symmetric
Hamiltonians with arbitrary spin S that are Marshall positive and can be simulated efficiently …

Although low-dimensional S= 1 antiferromagnets remain of great interest, difficulty in
obtaining high-quality single crystals of the newest materials hinders experimental research …

In this dissertation, we present two projects to study superconducting FeSe monolayer using
first-principles density functional calculations. Monolayer FeSe/SrTiO 3 system has very …

We study the Néel to four-fold columnar valence bond solid quantum phase transition in a
sign free S= 1 square lattice model. From quantum Monte Carlo simulations, we find …

This work focuses on numerical studies of quantum spin systems. These simple models are
known to exhibit a variety of phases, some of which have no classical counterpart. Phase …

The contents of this thesis encompass the research I conducted during the four years of my
doctoral studies. Under supervision of Philippe Corboz, I learned to understand and …