Thickness-Dependent Double-Epitaxial Growth in Strained SrTi0.7Co0.3O3-δ Films

Astera S Tang; Mehmet C Onbasli; Xueyin Sun; Caroline A Ross

doi:10.1021/acsami.7b18808

Thickness-Dependent Double-Epitaxial Growth in Strained SrTi_0.7Co_0.3O_3-δ Films

ACS Appl Mater Interfaces. 2018 Feb 28;10(8):7469-7475. doi: 10.1021/acsami.7b18808. Epub 2018 Feb 14.

Authors

Astera S Tang¹, Mehmet C Onbasli^{1

2}, Xueyin Sun³, Caroline A Ross¹

Affiliations

¹ Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
² Koç University, Department of Electrical and Electronics Engineering, Sarıyer, 34450 Istanbul, Turkey.
³ School of Materials Science and Engineering, Harbin Institute of Technology , P.O. Box 433, Harbin 150001, China.

PMID: 29442494
DOI: 10.1021/acsami.7b18808

Abstract

Perovskite-structured SrTi_0.7Co_0.3O_3-δ (STCo) films of varying thicknesses were grown on SrTiO₃(001) substrates using pulsed laser deposition. Thin films grow with a cube-on-cube epitaxy, but for films exceeding a critical thickness of about 120 nm, a double-epitaxial microstructure was observed, in which (110)-oriented crystals nucleated within the (001)-oriented STCo matrix, both orientations being epitaxial with the substrate. The crystal structure, strain state, and magnetic properties are described as a function of film thickness. Both the magnetic moment and the coercivity show maxima at the critical thickness. The formation of a double-epitaxial microstructure provides a mechanism for strain relief in epitaxially mismatched films.

Keywords: Co substitution; epitaxy; magnetism; perovskite; pulsed laser deposition; thin film.