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Updated: Jun 9, 2025
12:20
Sputter Growth and Characterization of Metamagnetic B2-ordered FeRh Epilayers
Published on: October 5, 2013
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Residual Ferromagnetic Regions Affecting the First-Order Phase Transition in Off-Stoichiometric Fe-Rh.
Alex Aubert1, Konstantin Skokov1, Andrei Rogalev2
1Functional Materials, Institute of Material Science, Technical University of Darmstadt, 64287 Darmstadt, Germany.
ACS Applied Materials & Interfaces
|October 29, 2024
Summary
FeRh stoichiometry critically impacts its first-order phase transition (FOPT) properties. Even minor iron (Fe) excess can suppress the FOPT, affecting magnetocaloric performance and revealing the role of residual ferromagnetic domains.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Magnetism
Background:
- FeRh is a reference material for studying first-order phase transitions (FOPT) due to its simple structure and significant magnetocaloric effect.
- Theoretical studies suggest Fe/Rh stoichiometry near equiatomic composition strongly influences FOPT characteristics, but experimental verification is limited.
Purpose of the Study:
- To experimentally investigate the effect of composition on the transitional hysteresis and FOPT behavior in FeRh.
- To understand the underlying mechanisms responsible for the stoichiometric sensitivity of FOPT in FeRh.
Main Methods:
- Investigated FeRh samples with varying Fe/Rh stoichiometry.
- Utilized element-specific X-ray magnetic circular dichroism (XMCD) to identify ferromagnetic contributions.
- Employed Mössbauer spectroscopy to detect Fe antisite defects.
Main Results:
- A Fe excess of 1 at.% induced a ferromagnetic state in a small portion of the sample, while 5 at.% completely eliminated the FOPT.
- XMCD indicated ferromagnetic contributions from residual FeRh ferromagnetic regions.
- Mössbauer spectroscopy confirmed the presence of Fe atoms at Rh sites (Fe antisite defects).
Conclusions:
- Stoichiometric deviations in FeRh significantly alter FOPT properties and magnetocaloric performance.
- Fe antisite defects are responsible for the formation of residual ferromagnetic domains, influencing FOPT behavior.
- The study elucidates the stoichiometric sensitivity of FOPT in FeRh, with implications for understanding FOPT dynamics and ferromagnetic domain roles.
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