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Decoherence-governed magnetic-moment dynamics of supported atomic objects
Jean-Pierre Gauyacq1, Nicolás Lorente
1Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ-Paris Sud, Université Paris-Saclay, F-91405 Orsay, France.
Summary
Substrate-induced decoherence in nanomagnets alters quantum tunneling, leading to stochastic magnetic switching. This effect enables experimental observation of magnetic state changes in atomic systems.
Area of Science:
- Condensed Matter Physics
- Quantum Mechanics
- Materials Science
Background:
- Nanomagnets exhibit spontaneous magnetic state changes due to quantum evolution of molecular magnetic moments.
- Environment-induced decoherence can suppress these spontaneous changes.
Purpose of the Study:
- To investigate the effect of substrate-induced decoherence on the magnetic evolution of supported atomic systems.
- To explain the observed stochastic magnetization switching in Fe on Cu2N/Cu (1 0 0) atomic structures.
Main Methods:
- Theoretical analysis of magnetic-moment evolution in the presence of substrate-induced decoherence.
- Comparison with experimental data for Fe atomic structures on Cu2N/Cu (1 0 0).
Main Results:
- Substrate-induced decoherence modifies, but does not eliminate, magnetic-moment evolution in small atomic systems.
- Rabi oscillations are replaced by irreversible decay, leading to stochastic switching.
- Switching rates show a 1/T thermal dependence and decrease with system size, matching experimental findings.
Conclusions:
- The observed stochastic magnetization switching is a result of substrate-induced decoherence.
- Quantum tunneling becomes the dominant switching mechanism only at extremely low temperatures (sub-μK).
- Experiments can detect switching in these systems because their dynamics are intermediate between full stability and rapid quantum tunneling.
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