Mechanisms of anisotropy control by strain in FePt/BaTiO3

M. CABABIE; A. LOPEZ PEDROSO; M. RODRIGUEZ; A. ROMAN; D. RUBI; L. B. STEREN; M. TORTAROLO; L. PIETRASANTA; J. GOMEZ; A. BUTERA; M. SIRENA

Glasgow

Conferencia; JEMS 2016; 2016

Nowadays, the design and fabrication of multiferroics (MF) is one of the main challenges for the development of oxide spintronics. Tuning the magnetic state of nanostructures by electric field or strains appears to be the key for low-energy devices. Magneto-electric and magneto-elastic coupling at interfaces between ferromagnetic (FM) and ferroelectric (FE) layers are at the origin of these phenomena. Both, the magnetic order and anisotropy of the FM component can be affected by the strains induced by the FM/FE lattice mismatch while charge transfer between both compounds can depend on the ferroelectric polarization of the structure. A variety of FM and FE have been combined into artificial MF, being the magnetic compounds generally oxides or transition metal alloys. In particular, FePt/BaTiO3 seems to be a very promising system. First-principle calculations revealed recently that important changes of magnetic anisotropy should be observed on the FePt overlayer when BaTiO3 is poled. The FePt disordered phase is a soft magnet, strongly sensitive to strains. Based on these knowledges we decided to investigate the structure FePt/BaTiO3. We do expect strain-induced effects originated at the BaTiO3 underlayer onto the magnetic properties of the FePt. On one hand, there is a large lattice mismatch between FePt and BaTiO3 lattices, ~8% and it is known that FePt magnetic properties are very sensitive to substrate-induced strains. On the other hand, we intend to observe more subtle effects in the FePt magnetization as the BaTiO3 overcomes different structural phase transitions below room temperature