Structural, transport, optical and electronic properties of Sr${}_2$CoNbO${}_6$ thin films

Abstract

We study the effect of substrate induced strain on the structural, transport, optical and electronic properties of Sr${}_2$CoNbO${}_6$ double perovskite thin films. The reciprocal space mapping, $\varphi$-scan and high-resolution $\theta$-2$\theta$ scans of x-ray diffraction patterns suggest the epitaxial nature and high-quality of the films deposited on various single crystal ceramic substrates. A systematic enhancement in the dc electronic conductivity is observed with increase in the compressive strain, while a sharp reduction in case of tensile strain, which are further supported by change in the activation energy and density of states near the Fermi level. The optical band gap extracted from two distinct absorption bands, observed in the visible-near infrared spectroscopy show a non-monotonic behavior in case of compressive strain while significant enhancement with tensile strain. Unlike the bulk Sr${}_2$CoNbO${}_6$ (Co${}^{3+}$ and Nb${}^{5+}$), we observe different valence states of Co namely 2+, 3+ and 4+, and tetravalent Nb (4$d^1$) in the x-ray photoemission spectroscopy measurements. Moreover, a reduction in the average oxygen valency with the compressive strain due to enhancement in the covalent character of Co/Nb--O bond is evident. Interestingly, we observe sharp Raman active modes in these thin films, which indicates a significant enhancement in structural ordering as compared to the bulk.

arXiv commentsubmitted

References in corpus (13)

• Structure and properties of functional oxide thin films: Insights from electronic-structure calculations
• Strain controlled oxygen vacancy formation and ordering in CaMnO${}_3$
• Misfit Strain Accommodation in Epitaxial ABO3 Perovskites: Lattice Rotations and Lattice Modulations
• Strain Control of Oxygen Vacancies in Epitaxial Strontium Cobaltite Films
• Strain-Induced Spin States in Atomically Ordered Cobaltites
• Tuning electronic structures via epitaxial strain in Sr2IrO4 thin films
• Coupled magnetic-ferroelectric metal-insulator transitions in epitaxially-strained SrCoO${}_3$ from first principles
• Strain-induced magnetic phase transition in SrCoO${}_{3-\delta }$ thin films
• Tuning the metal-insulator transition in NdNiO3 heterostructures via Fermi surface instability and spin-fluctuations
• Unraveling the magnetic interactions and spin state in insulating Sr${}_{2-x}$La${}_x$CoNbO${}_6$
• Anomalous magnetic and spin glass behavior in Nb substituted LaCo${}_{1-x}$Nb${}_x$O${}_3$
• Spin dynamics and unconventional magnetism in insulating La${}_{(1-2x)}$Sr${}_{2x}$Co${}_{(1-x)}$Nb${}_x$O${}_3$
• Strain induced changes of electronic properties of B-site ordered double perovskite Sr${}_2$CoIrO${}_6$ thin films

Cited by in corpus (3)

• Evidence of discrete energy states and cluster-glass behavior in Sr${}_{2-x}$La${}_x$CoNbO${}_6$
• Evolution of complex magnetic phases and metal-insulator transition through Nb substitution in La${}_{0.5}$Sr${}_{0.5}$Co${}_{1-x}$Nb${}_x$O${}_3$
• Structural and transport properties of La${}_{1-x}$Sr${}_x$Co${}_{1-y}$Nb${}_y$O${}_3$ thin films