Properties and microstructure of ultrathin (La,Ca)MnO{sub 3} films under different conditions of strain

Journal Article · Mon Nov 01 04:00:00 EST 2004 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.70.174111· OSTI ID:20664943

Yang, Z Q; Hendrikx, R; Aarts, J; Qin, Y L; Zandbergen, H W ^[1]

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1. Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands)

Ultrathin films of La{sub 1-x}Ca{sub x}MnO{sub 3} (x congruent with 0.33) in a thickness range below 10 nm were deposited by direct current (dc) magnetron sputtering on different substrates (001)SrTiO{sub 3} (STO), (001)LaAlO{sub 3} (LAO), and (110)NdGaO{sub 3} (NGO) in order to study the effects of strain in this thickness regime. The combined study of physical properties and microstructure by high-resolution electron microscopy (HREM) reveals that ultrathin ({<=}6 nm) strained films on STO can be grown in a body-centered-tetragonal structure not recognized previously. Such films do not show an insulator-metal (IM) transition. At slightly larger thickness, around 6 nm, the microstructure is different. Depending on the growth parameters we find either a structure involving MnO{sub 6}-octahedra tilted around two axes, in combination with the occurrence of twin boundaries as reported previously; or the bulk orthorhombic Pnma structure. In the latter case an IM transition is found at temperatures close to the bulk value. On lattice-matched NGO, the IM transition and bulk-like magnetoresistance effects are observed down to the lowest thickness investigated (3 nm). On LAO, which compresses the lattice, no IM transition is found even at a thickness of 15 nm, which is due to island-like growth, as confirmed by HREM observations.

• OSTI ID: 20664943
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 17 Vol. 70; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINATES
CALCIUM COMPOUNDS
DEPOSITION
DIRECT CURRENT
LANTHANUM OXIDES
MAGNETORESISTANCE
MAGNETRONS
MANGANESE COMPOUNDS
MICROSTRUCTURE
ORTHORHOMBIC LATTICES
SPUTTERING
STRAINS
STRONTIUM TITANATES
THICKNESS
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY