Phase transitions in frustrated quantum systems

Abstract Ginzburg-Landau theory of continuous phase transitions implicitly assumes that microscopic changes are negligible in determining the thermodynamic properties of the system. In this work we provide an example that clearly contrasts with this assumption. In particular, we consider the 2-cluster-Ising model, a one-dimensional spin-1/2 system that is known to exhibit a quantum phase transition between a magnetic and a nematic phase. By imposing boundary conditions that induce topological frustration we show that local order is completely destroyed on both sides of the transition and that the two thermodynamic phases can only be characterized by string order parameters. Having proved that topological frustration is capable of altering the nature of a system's phase transition, this result is a clear challenge to current theories of phase transitions in complex quantum systems.Abstract Ginzburg-Landau theory of continuous phase transitions implicitly assumes that microscopic changes are negligible in determining the thermodynamic properties of the system. In this work we provide an example that clearly contrasts with this assumption. In particular, we consider the 2-cluster-Ising model, a one-dimensional spin-1/2 system that is known to exhibit a quantum phase transition between a magnetic and a nematic phase. By imposing boundary conditions that induce topological frustration we show that local order is completely destroyed on both sides of the transition and that the two thermodynamic phases can only be characterized by string order parameters. Having proved that topological frustration is capable of altering the nature of a system's phase transition, this result is a clear challenge to current theories of phase transitions in complex quantum systems.

arXiv:2101.08807SciPost PhysicsFeb 24, 202215 citations

Phase Transitions in Quantum Systems

WORLD SCIENTIFIC eBooksNov 1, 20130 citations

Frustration-induced phase transitions in the spin- S orthogonal-dimer chain

Akihisa Koga, Norio Kawakami

We investigate quantum phase transitions in a frustrated orthogonal-dimer chain with an arbitrary spin $S>~1/2.$ When the ratio of the competing exchange couplings is varied, first-order phase transitions occur $2S$ times among distinct spin-gap phases. The introduction of single-ion anisotropy further enriches the phase diagram. The phase transitions described by the present model possess most of the essential properties inherent in frustrated quantum spin systems.We investigate quantum phase transitions in a frustrated orthogonal-dimer chain with an arbitrary spin $S>~1/2.$ When the ratio of the competing exchange couplings is varied, first-order phase transitions occur $2S$ times among distinct spin-gap phases. The introduction of single-ion anisotropy further enriches the phase diagram. The phase transitions described by the present model possess most of the essential properties inherent in frustrated quantum spin systems.

arXiv:cond-mat/0201518Physical review. B, Condensed matterMay 30, 200221 citations

Phase Transitions in Quantum Systems

WORLD SCIENTIFIC eBooksAug 1, 20040 citations

We investigate quantum phase transitions in a frustrated orthogonal-dimer chain with an arbitrary spin

S>~1/2.

When the ratio of the competing exchange couplings is varied, first-order phase transitions occur

2S

times among distinct spin-gap phases. The introduction of single-ion anisotropy further enriches the phase diagram. The phase transitions described by the present model possess most of the essential properties inherent in frustrated quantum spin systems.