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Multiferroic phase transition near room temperature in BiFeO3 films
I C Infante1, J Juraszek, S Fusil
1Unité Mixte de Physique CNRS/Thales, Campus de l'Ecole Polytechnique, 1 avenue Fresnel, 91767 Palaiseau, France.
Physical Review Letters
|December 21, 2011
Summary
Two bismuth ferrite polymorphs in thin films exhibit coupled structural, ferroelectric, and magnetic transitions near room temperature. This finding offers potential for advanced multiferroic device applications.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Solid State Chemistry
Background:
- Multiferroic materials exhibit multiple ferroic orders (ferroelectric, magnetic, etc.).
- Bismuth ferrite (BiFeO3) is a prominent multiferroic material with potential applications.
- Epitaxial strain in thin films can significantly alter material properties.
Purpose of the Study:
- To investigate the structural and multiferroic properties of BiFeO3 thin films on LaAlO3 substrates.
- To understand the coexistence of different polymorphs and their impact on material behavior.
- To explore the potential for novel applications based on coupled ferroic transitions.
Main Methods:
- Thin film growth using techniques like pulsed laser deposition or sputtering.
- Structural characterization using X-ray diffraction (XRD) and transmission electron microscopy (TEM).
- Multiferroic property measurements including dielectric, ferroelectric, and magnetic hysteresis loops as a function of temperature.
Main Results:
- Observation of two distinct BiFeO3 polymorphs with differing distortions.
- An abrupt structural change occurring concurrently with ferroelectric and magnetic transitions around 360 K.
- Transformation from a conventional to a nonconventional ferroelectric state and antiferromagnetic to paramagnetic transition.
Conclusions:
- The coexistence of polymorphs in BiFeO3 thin films leads to unique temperature-dependent properties.
- Coupled ferroic transitions near room temperature are promising for advanced applications.
- Potential for giant piezoelectric, magnetoelectric, and piezomagnetic responses.
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