Thema der Dissertation:
Investigation of Quantum Spin Systems with Auxiliary Particles
Investigation of Quantum Spin Systems with Auxiliary Particles
Abstract: The field of frustrated quantum magnetism is known both for its fascinating many-body phases, ranging from various symmetry-broken states to exotic quantum spin liquids that defy conventional paradigms of order. Examples of recent attention are models featuring quasiparticles of restricted mobility, commonly referred to as fractons. Despite their profound theoretical appeal, frustrated quantum magnets remain notoriously difficult to study, especially in the physically relevant case of three dimensions. In this defense talk, a general formalism called the 'pseudo-Majorana functional renormalization group' will be introduced to study frustrated quantum spin models with possible realizations of exotic new phases of matter. This approach leverages a spin representation in terms of Majorana fermions in combination with an approximate diagrammatic solution of the quantum many-body problem at finite temperature which improves upon state-of-the art approaches. Using this approach, the properties of several models in frustrated magnetism are discussed, in particular, previously proposed candidate models for classical fracton spin liquids are investigated under the influence of quantum fluctuations. By addressing the weaknesses of these models in stabilizing a quantum fracton phase, a new fracton model on a square lattice is proposed. This model stands as the first realization of a quantum fracton spin liquid arising solely from two-body spin interactions - a result confirmed by a combination of numerically exact quantum Monte Carlo simulations and the analytical solution of the corresponding lattice gauge theory. The results presented in this talk serve to improve the state of the art of numerical techniques in the study of frustrated magnetism and to push the existing limits in the realization of quantum fracton phases and their properties.
Zeit & Ort
16.12.2024 | 16:15
Hörsaal A (1.3.14)
Fachbereich Physik, Arnimallee 14, 14195 Berlin