Abstract
The quasi-two-dimensional nature of (LNO) thin films on (001) (STO) and (001) (LAO) substrates is examined. Although both samples undergo a metal-insulator transition with decreasing thickness, the spatial distributions of the insulating phase within the films differ from each other. The LNO cell volume of the insulating phase in LNO/STO is larger than that of the metallic phase, and the large cells remain at the interface in thick films with metallic conduction, suggesting a high oxygen-vacancy content at the interface. The cell volume of the insulating phase in LNO/LAO is smaller than that of the metallic phase, and the cell volume of the entire film changes coherently. The cell-volume decrease indicates that the bonding changes from bulklike to covalent.
- Received 29 March 2018
- Revised 19 June 2018
DOI:https://doi.org/10.1103/PhysRevB.98.014105
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