Buffer-layer enhanced structural and electronic quality in ferrimagnetic Sr2CrReO6 epitaxial films

Highly ordered epitaxial Sr2CrReO6 films of 20-nm and 175-nm thicknesses were deposited on SrTiO3 and (LaAlO3)0.3(Sr2AlTaO6)0.7 substrates and Sr2CrNbO6 buffer layers. Electronic measurements and scanning transmission electron microscopy images clearly show that the Sr2CrNbO6 buffer layers facilitate Cr/Re ordering near the interface, thus minimizing the number of defect states in the films. Arrhenius fits of the resistivity data give activation energies of 7.3–32 meV for films grown on non-buffered substrates, suggesting defect states are more conducting than Sr2CrReO6, whereas films grown on the Sr2CrNbO6 buffer layer have activation energies in the narrow range 38.6–42.1 meV.