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Quantum and classical relaxation in the proton glass
Yejun Feng1, C Ancona-Torres, T F Rosenbaum
1The James Franck Institute and Department of Physics, The University of Chicago, Chicago, Illinois 60637, USA.
Physical Review Letters
|December 13, 2006
Summary
Proton tunneling in ferroelectric and antiferroelectric crystals causes glassy behavior. This study links proton motion and hydrogen bond rearrangement to quantum tunneling, explaining relaxation dynamics.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Mechanics
Background:
- Ferroelectric RbH2PO4 and antiferroelectric NH4H2PO4 exhibit complex hydrogen-bond networks.
- Glassy behavior in crystalline solutions suggests unique relaxation mechanisms.
- Proton dynamics are crucial for understanding the material's properties.
Purpose of the Study:
- To investigate the glassy behavior in a crystalline solution of RbH2PO4 and NH4H2PO4.
- To identify the dominant relaxation mechanism at low temperatures.
- To quantitatively link potential energy landscape measurements with dielectric response.
Main Methods:
- Dielectric response characterization across seven decades of frequency.
- Neutron Compton scattering to measure the local potential energy landscape.
- Analysis of proton tunneling and collective proton motion.
Main Results:
- Glassy behavior confirmed, dominated by proton tunneling at low temperatures.
- Quantitative correlation between potential energy landscape and long-time relaxation.
- Logarithmic decay of polarization linked to quantum-mechanical action.
Conclusions:
- Proton tunneling is the primary relaxation mechanism in this hydrogen-bonded system.
- Neutron Compton scattering provides insights into the energy landscape governing proton dynamics.
- The study offers an analogy between proton tunneling and vortex tunneling in superconductors.
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