This thesis is a tour-de-force combination of analytic and computational results clarifying and resolving important questions about the nature of quantum phase transitions in one- and two-dimensional magnetic systems. The author presents a comprehensive study of a low-dimensional spin-half quantum antiferromagnet (the J-Q model) in the presence of a magnetic field in both one and two dimensions, demonstrating the causes of metamagnetism in such systems and providing direct evidence of fractionalized excitations near the deconfined quantum critical point. In addition to describing significant new research results, this thesis also provides the non-expert with a clear understanding of the nature and importance of computational physics and its role in condensed matter physics as well as the nature of phase transitions, both classical and quantum. It also contains an elegant and detailed but accessible summary of the methods used in the thesisexact diagonalization, Monte Carlo, quantumMonte Carlo and the stochastic series expansionthat will serve as a valuable pedagogical introduction to students beginning in this field.

Nominated as an outstanding PhD thesis by Boston University New results on quantum phase transitions in magnetic systems such as metamagnetism and deconfined quantum criticality Accessible introduction to condensed matter physics focusing on phase transitions Highlights women computational physicists, focusing on Arianna Rosenbluth and the Metropolis Algorithm Provides a detailed pedagogical guide to quantum Monte Carlo

Autorentext
Adam Iaizzi received his PhD from Boston University in 2018. He now holds a postdoctoral position at National Taiwan University.

Inhalt
Chapter1. Introduction.- Chapter2. Saturation Transition in the 1D J-Q Model.- Chapter3. Saturation Transition in the 2D J-Q Model.- Chapter4. Signatures of Deconned Quantum Criticality in the 2D J-Q-h Model.- Chapter5. Methods.- Chapter6. Conclusions.