Magnetotransport anisotropy in lattice-misfit-strained ultrathin La2/3Ca1/3MnO3 films epitaxially grown on (110)-oriented SrTiO3 and LaAlO3 substrates

Abstract

(110)-Oriented manganite thin films are essential for studies on the interface effects concerning spin-polarized electron injection, especially the proximity effect with high temperature superconducting cuprates. However, due to the peculiarity of the (110) plane, an atomically smooth surface generally can only sustain up to a quite low film thickness. Therefore, anisotropy along the two crystallographically asymmetric [001] and [11¯0] in-plane directions in ultrathin (110)-oriented manganite films are worthy of a careful investigation. Here, studies on the magnetotransport anisotropy of (110)-oriented epitaxial La2/3Ca1/3MnO3 (LCMO) thin films of 20 nm thickness grown by pulsed laser deposition are reported. Both SrTiO3 (STO) and LaAlO3 (LAO) substrates were adopted to highlight the lattice-misfit-strain effects. While in LCMO/STO film, the magnetic easy axis is along the [11¯0] direction, in LCMO/LAO film the [001] direction is easier. Accordingly, the resistivity and magnetoresistance measured along the easy axes are lower. The correlation between the magnetic and transport anisotropy then has been undoubtedly demonstrated. For the LCMO films on STO, property evolutions with temperature and magnetic field are free from fine features, and thus clear and easily understood, making STO a more appropriate substrate for interface studies in (110)-oriented heterostructures.