Abstract
BiFeO3 (BFO) and LaxSryMnzO3 (LSMO) films were epitaxially grown on SrTiO3 (100) substrates by r.f. magnetron sputtering with various oxygen gas flow ratios (FO2). Compositional ratios of each atom in both of BFO and LSMO could be controlled kept to around 10 at.% by changing FO2. Adjusting the compositional ratio to La0.35Sr0.15Mn0.5O3 not only increase Tc of LSMO but also produces sufficient oxygen to form a perovskite lattice. For an LSMO/BFO heterostructure, detailed observation by cross sectional transmission electron microscopy (TEM) revealed that the lattice of rhombohedral (SG: R-3c) LSMO was shrank by a clamping effect from the SrTiO3 substrates, and then the BFO was grown in two layers: (i) an interfacial BFO layer (7 nm thick) with evenly shrunk a-axis and c-axis, and (ii) an upper BFO layer (25 nm thick) expanded along the c-axis. Neither misfit strain nor dislocations appeared at the interface between the shrunken BFO and LSMO layers, and these heterostructures did not show exchange bias. These results suggest that BFO is suitable for a tunneling barrier combine with LSMO electrode.
Highlights
Heterostructures of BiFeO3 (BFO) and La0.7Sr0.3Mn1.0O3 have attracted interest because they exhibit interfacial magnetism at room temperature (RT). 1–3 BFO has shows G-type antiferromagnetism together with ferroelectricity, so it is one of the so-called multiferroics, and it cerates magneto-electric (ME) coupling at RT;[4] it can be expected that exchange bias[5] and interfacial magnetism of BFO/La0.7Sr0.3Mn1.0O3 can be controlled by switching spontaneous polarization by applying a voltage to the BFO layer
For an LSMO/BFO heterostructure, detailed observation by cross sectional transmission electron microscopy (TEM) revealed that the lattice of rhombohedral (SG: R-3c) LSMO was shrank by a clamping effect from the SrTiO3 substrates, and the BFO was grown in two layers: (i) an interfacial BFO layer (7 nm thick) with evenly shrunk a-axis and c-axis, and (ii) an upper BFO layer (25 nm thick) expanded along the c-axis
LSMO and BFO films and their heterostructures were prepared by reactive r.f. magnetron sputtering method on SrTiO3 (100) substrates and their structural and magnetic properties were systematically investigated
Summary
Heterostructures of BiFeO3 (BFO) and La0.7Sr0.3Mn1.0O3 have attracted interest because they exhibit interfacial magnetism at room temperature (RT). 1–3 BFO has shows G-type antiferromagnetism together with ferroelectricity, so it is one of the so-called multiferroics, and it cerates magneto-electric (ME) coupling at RT;[4] it can be expected that exchange bias[5] and interfacial magnetism of BFO/La0.7Sr0.3Mn1.0O3 can be controlled by switching spontaneous polarization by applying a voltage to the BFO layer. In the case of a heterostructure, epitaxial strains are built in at the interface for compensating the lattice misfit, which influences the interfacial magnetic property; the interfacial structure in the cases of BFO and La0.7Sr0.3Mn1.0O3 has not yet been investigated in detail Epitaxial strain affects both magnetic and electric properties; strains are necessary to analyze by cross-sectional transmission electron microscopy (TEM) observation. There are many reports of LSMO films prepared by pulsed laser deposition (PLD) and laser ablation methods.[8,9] In the case of reactive sputtering method,[10,11,12,13,14,15,16] it is tentatively considered that the assistance of oxygen plasma directly affects oxidation state of the sputtered particles This phenomenon indicates the density of the oxygen plasma changes the physical properties of LSMO and BFO. The interfacial structure between BFO and LSMO was observed by a cross-sectional transmission electron microscopy (TEM)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
