Microstructure and ferromagnetic property in CaRuO3 thin films with pseudoheterostructure

CaRuO3 thin films were synthesized on SrTiO3 substrates by pulsed laser deposition. Detailed microstructure analysis by transmission electron microscopy revealed the pseudoheterostructure in CaRuO3 films. It consists of a coherently strained cubic CaRuO3 layer contacted with substrate, as well as a strained orthorhombic CaRuO3 layer. The orthorhombic CaRuO3 layer is composed of two types of domains. The ferromagnetic property of the pseudoheterostructure CaRuO3 was revealed by superconducting quantum interference device measurement. This is due to the cubic CaRuO3 layer, which is supported by first-principle calculations. The formation mechanism of pseudoheterostructure in ultrathin CaRuO3 thin films was proposed. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3422476]