Surface reconstructions and modified surface states in La1-xCaxMnO3


The unique functionalities present at surfaces and interfaces of complex oxides have attracted intense research in the past decade. Yet, the fundamental mechanisms underpinning functionality are often elusive, especially in doped manganites, limiting their implementation in functional electronic devices such as memristors and spin valves. Here, we present a local probe-based study on mixed-terminated La5/8Ca3/8MnO3 (LCMO) films, and reveal surface metallicity in a thin film grown by pulsed-laser deposition. Using first-principles density-functional theory calculations with Hubbard correction that are more accurate to capture effects of correlation in these systems, we show that for Ca-segregated (001) LCMO surfaces the (La,Ca)O-site terminated surfaces are half metallic due to delocalized Mn-d states populating the Fermi level, whereas the MnO2-site terminated surfaces exhibit a half-metallic or insulating character depending on the type of surface reconstruction. Computations not only explain the current measurements, but also explain other recent surface measurements on LCMO thin films, leading to a coherent picture of how the crucial link between surface segregation and Jahn-Teller couplings in the manganese oxides tune the surface electronic/magnetic structure, thereby pointing to the fine control of transport and magnetism at the conductive oxide surface independent of the bulk.




Materials Science


Vasudevan, RK; Dixit, H; Tselev, A; Qiao, L; Meyer, TL; Cooper, VR; Baddorf, AP; Lee, HN; Ganesh, P; Kalinin, SV

nossos autores


The experimental work was supported by the U.S. Department of Energy (DOE), Office of Science (OS), Basic Energy Sciences, Materials Sciences and Engineering Division (R.K.V., S.V.K., T.M., H.N.L.). DFT work was supported by the OS Early Career Research Program (V.R.C., H.D.). Research was conducted at the Center for Nanophase Materials Sciences, which also provided support (A.P.B., P.G.) and is a DOE OS User Facility. This research used resources of the National Energy Research Scientific Computing Center, a DOE OS User Facility supported by the OS of the U.S. DOE under Contract No. DE-AC02-05CH11231. A.T. acknowledges CICECO-Aveiro Institute of Materials, ERDF Grant No. POCI-01-0145-FEDER-007679 (FCT Ref. No. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate cofinanced by FEDER under the PT2020 Partnership Agreement.

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