MnO6 Octahedral Tilt Control of Emergent Phenomena at LaMnO3/SrMnO3 Interfaces

Abstract

Emergent phases at the interfaces in strongly correlated oxide hetero structures display novelproperties not akin to those of constituting materials. The interfacial ferromagnetism in LaMnO3/SrMnO3 (LMOm/SMOn) superlattices (SLs) is usually considered to be a result of the interfacial charge transfer. We report a decisive role of atomic interface structure in the development of emergent magnetism and phonon transport in (LMO)m/(SMO)n SLs (m/n=1, 2). The observed common octahedral network with MnO6-tilt-free interfaces in m/n=1 SLs suppresses interfacial electron transfer and enhances thermal (phonon) conductivity. For m/n=2 SLs two distinct LMO and SMO lattices result in an MnO6 tilt mismatch, which enhances the emergent ferromagnetism and suppresses thermal conductivity. Furthermore, the interface thermal conductance increases strongly from 0.29 up to 1.75 GW/m2K in SLs with (m/n=2) and without (m/n=1) tilt mismatch, respectively. Experimental results, fully supported by first principle calculations, emphasize a fundamental role of electron-spin-lattice interplay at interfaces and open new avenues of lattice engineering of emergent phases.