Competing Misfit Relaxation Mechanisms in Epitaxial Correlated Oxides

Abstract

Strain engineering of functional properties in epitaxial thin films of strongly correlated oxides exhibiting octahedral-framework structures is hindered by the lack of adequate misfit relaxation models. Here we present unreported experimental evidence of a four-stage hierarchical development of octahedral-framework perturbations resulting from a progressive imbalance between electronic, elastic, and octahedral tilting energies in La(0.7)Sr(0.3)MnO(3) epitaxial thin films grown on SrTiO(3) substrates. Electronic softening of the Mn-O bonds near the substrate leads to the formation of an interfacial layer clamped to the substrate with strongly degraded magnetotransport properties, i.e., the so-called dead layer, while rigid octahedral tilts become relevant at advanced growth stages without significant effects on charge transport and magnetic ordering.

Correlating interfacial octahedral rotations with magnetism in (LaMnO3+δ)N/(SrTiO3)N superlattices

“…In recent studies, orbital ordering, 37 polar discontinuity 38,39 , magnetic coupling to the titanate layer, 40 stoichiometry 41,42 and so on, have all been evidenced to couple to the interface magnetic property of the manganite layer, while a unified scenario is still lacking. Some recent studies on La 0.67 Sr 0.33 MnO 3 /SrTiO 3 interfaces have merged on the finding of increased amount of Mn 3 þ near the interface [43][44][45] and 3z 2 À r 2 orbital ordering irrespective of the strained state 37,45,46 . Our study suggests that the reconstructed OOR at the interface is another nontrivial factor in determining the interfacial magnetic property.…”

Giant Enhancement of Magnetic Anisotropy in Ultrathin Manganite Films via Nanoscale 1D Periodic Depth Modulation

“…4(e)), and point to the critical role of the MnO 6 distortion in controlling MCA. Such high sensitivity of manganites to the MnO 6 distortion can thus be utilized as a powerful tool to tailor their electronic and magnetic states at the nanoscale [25][26][27][36][37][38].…”

Enhanced conduction and ferromagnetic order at (100)-type twin walls inLa0.7Sr0.3MnO3Balcells1, Paradinas2, Bagués3 et al. 2015Phys. Rev. BSelf Cite10060View full textAdd to dashboardCite

“…The topography of as-grown films consists of atomically flat terraces with a roughness below 0.3Å bounded by unit cell (∼4Å) height steps. Among the {100} and {110} TWs allowed in the m3m →3m ferroelastic transition [15], only those with (100) and (010) orientations, perpendicular to the substrate, are present in these films [25,26]. The lateral twin size increases as t 1/2 [26].…”

“…The twinned film thus can be viewed as a self-organized nanostructure consisting of 1 nm thick sheets of strongly compressed LSMO embedded in matrix of tensilely strained LSMO. In our GPA analysis E TW/TD xx is defined relative to the TD, which is fully in-plane strained by the STO substrate [25] (misfit δ ∼ 0.6); therefore, the effective compression relative to the bulk LSMO phase is of ∼ − 2.9%.…”

“…The TDs remain fully in-plain strained by the substrate in the explored thickness range [25]. In-plane electrical resistivity and magnetization measurements of these samples are reported elsewhere [25].…”