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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Low temperature ferromagnetism in chemically ordered FeRh nanocrystals.
A Hillion1, A Cavallin, S Vlaic
1Laboratoire de Physique de la Matière Condensée et Nanostructures, UMR-CNRS 5586 and Université Lyon 1, 69622 Villeurbanne cedex, France.
Physical Review Letters
|March 12, 2013
Summary
Ferromagnetic order persists down to 3 K in 3.3 nm iron-rhodium (FeRh) nanocrystals, unlike bulk materials. This finding is linked to size-induced structural relaxation in the embedded nanoparticles.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Previous studies on iron-rhodium (FeRh) bulk, thin films, and nanoparticles have shown varying magnetic properties.
- Understanding the magnetic behavior of nanomaterials is crucial for developing advanced electronic devices.
Purpose of the Study:
- To investigate the magnetic properties of size-selected FeRh nanocrystals.
- To determine the critical temperature for ferromagnetic order in 3.3 nm FeRh nanocrystals.
Main Methods:
- Synthesis of size-selected 3.3 nm diameter FeRh nanocrystals embedded in an amorphous carbon matrix.
- Structural characterization using extended X-ray absorption spectroscopy (XAS).
- Magnetic measurements using X-ray magnetic dichroism (XMD) and superconducting quantum interference device (SQUID).
Main Results:
- Ferromagnetic order was observed to persist down to 3 K in the 3.3 nm FeRh nanocrystals.
- The nanoparticles exhibited a B2 structure with alternating Fe and Rh atomic layers.
- XMD and SQUID measurements confirmed ferromagnetic alignment of Fe (3 μB) and Rh (1 μB) magnetic moments.
Conclusions:
- Finite-size induced structural relaxation plays a key role in maintaining ferromagnetic order at low temperatures in FeRh nanocrystals.
- These findings contrast with bulk FeRh and suggest unique magnetic behaviors in nanomaterials.
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