In-plane strain modulated magnetization and magnetoelectric effect in La_(0.7)Sr_(0.3)MnO_3-BaTiO_3 and La_(0.7)Sr_(0.3)MnO_3-BaTiO_3-BiFeO_3 multilayer's

摘要

La_(0.7)Sr_(0.3)MnO_3-BaTiO_3(LSMO/BTO) and La_(0.7)Sr_(0.3)MnO_3-BaTiO_3-BiFe_3 (LSMO/BTO/BFO) multilayer thin films are deposited on STO (100) substrate by pulsed laser deposition. In-plane lattice mismatch induced strain is thoroughly investigated with the conclusion, that upper BTO layer of bilayer resides in high strained state, while upper BFO layer of trilayer remains under partially relaxed state. Significantly higher value (～20) of dielectric constant is observed for LSMO/BTO bilayer in compliance with its higher (12.28 μC/cm~2) in-plane strain induced interfacial polarization, which exceeds (2.06 μC/cm~2), the observed value of polarization for LSMO/BTO/BFO trilayer. In LSMO/BTO bilayer, antiferromagnetic LSMO phase coexists due to the existence of strong tensile strain between the interfaces, which causes the reduction in value of saturation magnetization up to 50.76 emu/cm~3 in comparison to 145.01 emu/cm~3 for LSMO/BTO/BFO trilayer. The maximum value of linear magnetoelectric coefficient (α31) observed for LSMO/BTO bilayer is 24.77 mV/cm-Oe, which is higher in comparison to 19.54 mV/cm-Oe for LSMO/BTO/BFO trilayer, where the upper layer undergoes less strain in comparison to the bilayer.