Deconfined quantum criticality of the O(3) nonlinear {sigma} model in two spatial dimensions: A renormalization-group study

Journal Article · Fri Jul 15 04:00:00 EDT 2005 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.72.035109· OSTI ID:20719141

Kim, Ki-Seok ^[1]

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1. Korea Institute for Advanced Study, Seoul 130-012 (Korea, Republic of)

We investigate the quantum phase transition of the O(3) nonlinear {sigma} model without Berry phase in two spatial dimensions. Utilizing the CP{sup 1} representation of the nonlinear {sigma} model, we obtain an effective action in terms of bosonic spinons interacting via compact U(1) gauge fields. Based on the effective field theory, we find that the bosonic spinons are deconfined to emerge at the quantum critical point of the nonlinear {sigma} model. It is emphasized that the deconfinement of spinons is realized in the absence of Berry phase. This is in contrast to the previous study of Senthil et al. [Science 303, 1490 (2004)], where the Berry phase plays a crucial role, resulting in the deconfinement of spinons. It is the reason why the deconfinement is obtained even in the absence of the Berry phase effect that the quantum critical point is described by the XY ('neutral') fixed point, not the IXY ('charged') fixed point. The IXY fixed point is shown to be unstable against instanton excitations and the instanton excitations are proliferated. At the IXY fixed point it is the Berry phase effect that suppresses the instanton excitations, causing the deconfinement of spinons. On the other hand, the XY fixed point is found to be stable against instanton excitations because an effective internal charge is zero at the neutral XY fixed point. As a result the deconfinement of spinons occurs at the quantum critical point of the O(3) nonlinear {sigma} model in two dimensions.

• OSTI ID: 20719141
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 3 Vol. 72; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACTION INTEGRAL
ANTIFERROMAGNETISM
CRITICALITY
EXCITATION
FIELD THEORIES
NONLINEAR PROBLEMS
PARAMAGNETISM
PHASE TRANSFORMATIONS
RENORMALIZATION
SIGMA MODEL
U-1 GROUPS