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Magnetic exchange splitting in Fe above the Curie temperature
M Pickel1, A B Schmidt, M Weinelt
1Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany.
Physical Review Letters
|September 28, 2010
Summary
Researchers studied magnetic splitting in iron films. Findings show local magnetic moments persist above the Curie temperature, challenging previous assumptions about magnetic phase transitions.
Area of Science:
- Condensed Matter Physics
- Surface Science
- Magnetism
Background:
- The behavior of magnetic materials near their Curie temperature (T(C)) is crucial for understanding magnetic phase transitions.
- Investigating electronic states provides insights into the underlying magnetic properties.
Purpose of the Study:
- To examine the magnetic exchange splitting of electronic states in a 7-monolayer iron (Fe) film on a copper (Cu)(001) substrate.
- To determine how these electronic states behave below and above the Curie temperature (T(C)).
Main Methods:
- Utilized image-potential surface states as a sensitive probe.
- Experimentally measured magnetic exchange splitting and spin polarization.
- Analyzed spin-integrated linewidth variations with temperature.
Main Results:
- Observed a vanishing spin splitting and spin polarization at T(C), indicating the breakdown of long-range magnetic order.
- Found that the magnetic exchange splitting persisted up to 1.2T(C), not changing abruptly at the Curie temperature.
- Noted that the spin-integrated linewidth decreased smoothly with increasing temperature, showing no signature of the magnetic phase transition.
Conclusions:
- Experimental results align with theoretical predictions regarding magnetic phase transitions.
- Long-range magnetic order disappears at T(C), but local magnetic moments remain unaffected.
- The valence electronic structure of the Fe film is largely unchanged by the transition at T(C).
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