Simultaneous enhancements of polarization and magnetization in epitaxial Pb(Zr0.52Ti0.48)O-3/La0.7Sr0.3MnO3 multiferroic heterostructures enabled by ultrathin CoFe2O4 sandwich layers

Article

关键词: THIN-FILMS;    ANISOTROPY;    STRESS;    MODEL;   

DOI  :  10.1103/PhysRevB.91.054419

来源: SCIE

【 摘 要 】

Layered thin films of Pb(Zr1-xTix)O-3 (PZT) and LaxSr1-xMnO3 (LSMO) are well-known multiferroic systems that show promise for numerous applications including data storage devices and spintronics. In this work, structure-property relationships are explored in novel PZT/CoFe2O4 (CFO)/LSMO heterostructures with optimized ferroic properties. High quality, epitaxial PZT/CFO/LSMO heterostructures with the thickness of the CFO layer varying from 0 to 50 nm were grown on SrTiO3 (100) substrates using an optimized pulsed laser deposition technique. An ultrathin (10-20 nm) CFO layer was found to simultaneously improve the ferromagnetic and ferroelectric (FE) characteristics of the system through distinct mechanisms. The increase in magnetization and magnetic coercivity in the CFO-containing samples was associated with a tetragonal distortion of the CFO lattice under epitaxial strain, while perpendicular anisotropy generated by the distortion stabilized an out-of-plane orientation of the easy axis ofmagnetization in the thinnest CFO layers. Trapped charge at the CFO/PZT interface in PZT/CFO/LSMO induced an internal built-in field in the heterostructures, resulting in the accumulation of higher switched charges during voltage cycling and enhanced polarization in the samples over PZT/LSMO. An increase in electric coercivity was also observed in the CFO-containing heterostructures, and is discussed in terms of a dielectric/FE layered capacitor model. Above a critical thickness, similar to 50 nm, the presence of a CFO layer has a negative effect on both magnetization and polarization in PZT/CFO/LSMO as compared to PZT/LSMO.

【 授权许可】

Free