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Harmonic phase in polar liquids and spin ice
1London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, 17-19 Gordon Street, London, WC1H 0AJ, UK. s.t.bramwell@ucl.ac.uk.
Nature Communications
|December 14, 2017
Summary
This study reveals a new state of matter, the "harmonic phase," observed in spin ice. This phase, described by Onsager
Area of Science:
- Condensed Matter Physics
- Physical Chemistry
Background:
- Many liquid-like states defy mean-field theory predictions of ordering at low temperatures.
- Correlated magnetic states like spin ice are often described as Coulomb phases.
- Onsager's theory of the reaction field explains order evasion in polar liquids.
Purpose of the Study:
- To investigate the low-temperature behavior of systems that evade mean-field ordering.
- To connect Onsager's theory to the concept of Coulomb phases in magnetism.
- To identify and characterize a novel low-temperature state in dipolar systems.
Main Methods:
- Theoretical analysis of Onsager's reaction field theory at low and finite temperatures.
- Experimental observation in spin ice, a dipolar lattice system.
- Characterization of the emergent geometrical state using harmonic functions.
Main Results:
- At low temperatures, Onsager's theory aligns with Coulomb phase descriptions.
- At finite temperatures, Onsager's theory describes a distinct 'harmonic phase' governed by harmonic functions.
- The harmonic phase was experimentally observed in spin ice.
Conclusions:
- Onsager's theory provides a framework for understanding the harmonic phase.
- The harmonic phase represents a distinct geometrical state relevant to dipolar liquids.
- This finding bridges concepts from magnetism and physical chemistry.
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