SrRuO3 Epitaxial Films Research Articles

Impact of microstructure on transport properties of nanometric epitaxial SrRuO3 films

We report on structural and magnetotransport properties of SrRuO3 films—grown on SrTiO3—and its dependence on thickness t (4 nm⩽t⩽320 nm). At early stages of film growth, a self-ordered finger-like pattern of growth units is formed and gives rise to a prominent in-plane anisotropy of transport properties. We argue that this behavior originates from defective regions formed at grain-merging regions and we show that appropriate annealing allows eliminating these defects. In addition, there is a progressive shift towards a lower temperature of the characteristic feature associated with the onset of the ferromagnetism. Since the films are fully strained, we argue that both effects are not associated to homogeneous cell modifications, but reflects the microstructural disorder concomitant to the island growth observed at early stages of film growth, the resulting stress distribution and the polymorphism of SrRuO3.

Early-stage growth behavior of laser ablated epitaxial SrRuO3 thin films on SrTiO3(001)

Microstructural changes in epitaxial SrRuO3 films grown on SrRuO3 (001) during early stages of growth by pulsed laser deposition were studied mainly using synchrotron x-ray scattering. At a very early stage of growth, the film is composed of a single (110) domain, in contrast to double (110) domains in later stages of growth. This domain evolution appears to be closely linked to a significant enhancement of crystalline ordering in the in-plane direction.

Lattice distortion and uniaxial magnetic anisotropy in single domain epitaxial (110) films of SrRuO3

Single domain epitaxial (110) films of SrRuO3 exhibit uniaxial magnetic anisotropy instead of the biaxial anisotropy observed in the bulk material. The magnetic easy axis for the film is along the orthorhombic [010] direction below TC, and it rotates toward the [110] perpendicular direction as temperature decreases. The [100] direction, which is also magnetically “easy” in the bulk, becomes “hard” in the film. X-ray diffraction experiments show that this unique transformation of magnetic anisotropy is related to a distortion from the bulk orthorhombic lattice into a triclinic structure in the epitaxial film, such that the lattice along the [010] direction expands while its [100] counterpart contracts. The distortion appears to arise from rotation and tilt of RuO6 octahedra. The finding indicates that the magnetic anisotropy in epitaxial SrRuO3 films is rooted in the crystalline anisotropy influenced by strong spin–orbit interactions.