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SUMMARY:Giant sharp magnetoelectric switching in multiferroic epitaxial La
 0.67Sr0.33MnO3 on BaTiO3 - Neil Mathur\, Department of Materials Science\,
  University of Cambridge
DTSTART:20061004T101500Z
DTEND:20061004T111500Z
UID:TALK5416@talks.cam.ac.uk
CONTACT:Michael Sutherland
DESCRIPTION:Magnetoelectric coupling permits a magnetic order parameter to
  be addressed electrically or vice versa\, and could find use in data stor
 age\, field sensors and actuators. Coupling constants for single phase mat
 erials such as chromium dioxide\, boracites and manganites are typically a
 s low as10^-12^ to 10^-9^ s m^-1^\, e.g. because the polarisations and 
 magnetisations are small. Two phase multiferroics with strain mediated cou
 pling\, such as laminates\, composites and epitaxial nanostructures\, are 
 more promising because each phase may be independently optimised. The resu
 lting magnetoelectric switching can be larger\, e.g. 10^-8^ s m^-1^\, but 
 it is not sharp because clean coupling is precluded by the complexity of t
 he microstructures and concomitant strain fields. I will report a giant sh
 arp magnetoelectric effect at a single epitaxial interface between a 40 nm
  ferromagnetic stress-sensitive La0.67Sr0.33MnO3 film\, and a 0.5 mm BaTiO
 3 substrate that is ferroelectric\, piezoelectric and ferroelastic. By app
 lying a small electric field (4 10 kV cm^-1^) across the entire structure\
 , persistent changes in film magnetisation of up to 65% are achieved near 
 the BaTiO3 structural phase transition at ~200 K. This represents a giant 
 magnetoelectric coupling (2.3 X 10^-7^ s m^-1^) that arises from strain fi
 elds due to ferroelastic non-180° domains whose presence are confirmed us
 ing x-ray diffraction. The coupling persists over a wide range of temperat
 ures including room temperature\, and could therefore inspire a range of s
 ensor and memory applications.
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Department of Physics
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