Multiversality and Unnecessary Criticality in One Dimension.

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Statistical Mechanics

Background:

• Spin ladders are key models in condensed matter physics.
• Understanding critical phenomena in quantum systems is crucial.
• Predicting properties of critical surfaces from flanking phases is a standard approach.

Purpose of the Study:

• To present novel microscopic models of spin ladders.
• To investigate spin ladder models exhibiting unusual critical surfaces.
• To explore phenomena like multiversality and unnecessary criticality.

Main Methods:

• Microscopic modeling of spin ladders.
• Abelian bosonization techniques.
• Density-matrix renormalization-group (DMRG) simulations.

Main Results:

• Discovered spin ladder models with continuous critical surfaces.
• Observed critical surfaces whose properties are not inferable from flanking phases.
• Identified instances of multiversality and unnecessary criticality.

Conclusions:

• The existence and properties of these critical surfaces are unusual.
• Multiversality and unnecessary criticality represent novel critical phenomena.
• Further generalization of these findings is explored.