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Possible quantum diffusion of polaronic muons in Dy(2)Ti(2)O(7) spin ice
P Quémerais1, P McClarty, R Moessner
1Max-Planck-Institut for the Physics of Complex Systems, Dresden, Germany.
Physical Review Letters
|September 26, 2012
Summary
Quantum diffusion of muons explains relaxation rates in magnetic pyrochlores. Low-temperature plateaus result from muon tunneling, not magnetic fluctuations, with a crossover to hopping at higher temperatures.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Magnetism
Background:
- The magnetic pyrochlore Dy(2)Ti(2)O(7) exhibits complex magnetic properties.
- Muon spin relaxation (µSR) is a sensitive probe of magnetic dynamics.
Purpose of the Study:
- To interpret zero-field muon relaxation rate measurements in Dy(2)Ti(2)O(7).
- To elucidate the mechanism behind the observed low-temperature plateau in relaxation rates.
Main Methods:
- Analysis of zero-field muon relaxation rate data.
- Modeling muon diffusion via quantum tunneling and hopping.
Main Results:
- The low-temperature plateau (< 7 K) is attributed to coherent muon tunneling in a disordered spin state.
- A crossover from tunneling to incoherent activated hopping occurs around T* = 50 K.
- The observed behavior is distinct from persistent low-temperature magnetic fluctuations.
Conclusions:
- Muon diffusion, specifically quantum tunneling, governs the relaxation rate in Dy(2)Ti(2)O(7).
- This interpretation provides a unified understanding of the temperature dependence of muon relaxation.
- Comparison with muonium diffusion in KCl highlights material-specific quantum transport phenomena.
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