Interfacial electronic and magnetic properties of a Y${}_{0.6}$Pr${}_{0.4}$Ba${}_2$Cu${}_3$O${}_7$/La${}_{2/3}$Ca${}_{1/3}$MnO${}_3$ superlattice

Resonant soft x-ray absorption spectroscopy and diffuse neutron scattering were used to study the interfacial properties of Y${}_{0.6}$Pr${}_{0.4}$Ba${}_2$Cu${}_3$O${}_7$/La${}_{2/3}$Ca${}_{1/2}$MnO${}_3$ superlattices. Dramatic changes from the bulk in the spectral line shape, energy position, and linear-polarization dependence of the Cu L${}_3$-edge reveal a striking interfacial modification. The similarities to the case without Pr substitution confirm the strongly hybridized covalent Cu-O-Mn bond as the underlying driving mechanism. On the other hand, relative differences, including reduced charge transfer and interfacial orbital reconstruction, are observed and attributed to raising of the Fermi level of the cuprate layer with Pr substitution. Neutron reflectometry reveals an oscillatory behavior in the rapidly increasing diffuse scattering with decreasing temperature. Temperature- and field-dependent measurements indicate that the origin is associated with the buckling caused by the structural phase transition of the SrTiO${}_3$ substrate rather than the superconducting or magnetic transition.

Figure 1

Resistance vs temperature without magnetic field (solid curve) and with a magnetic field (dashed curve) of 6 T perpendicular to the film surface.

Figure 2

Normalized linearly polarized x-ray absorption spectra at the Cu L${}_3$-edge taken in (upper curves) bulk-sensitive fluorescence mode and (lower curves) interface-sensitive total electron yield mode. Dashed lines are guides to eyes.

Figure 3

Off-specular neutron reflectivity taken at room temperature, 90 K, and 7 K with a 15 mT cooling field applied parallel to the layers and perpendicular to the beam.

Figure 4

Temperature-dependent unpolarized neutron transverse scans at Q${}_z=0.0139$ ${\AA }^{-1}$ (right below the critical edge). Error bars correspond to $\pm$$\sigma$. Lines are guides to the eye.

Figure 5

Field-dependent non-spin-flip scattering of polarized neutron transverse scans at Q${}_z=0.035$ ${\AA }^{-1}$ with spin-up (solid square) and spin-down (open circle) neutrons. Error bars correspond to $\pm$$\sigma$. Lines are guides to the eye.