Relaxor characteristics at the interfaces of ${\text{NdMnO}}_3/{\text{SrMnO}}_3/{\text{LaMnO}}_3$ superlattices

We have investigated the magnetic properties of transition-metal oxide superlattices with broken inversion symmetry composed of three different antiferromagnetic insulators, $\left[{\text{NdMnO}}_3/{\text{SrMnO}}_3/{\text{LaMnO}}_3\right]$. In the superlattices studied here, we identify the emergence of a relaxor, glassylike behavior below $T_{\text{SG}}=36\text{K}$. Our results offer the possibility to study and utilize magnetically metastable devices confined at nanoscale interfaces.

Figure 1

(Color) (a) Schematic drawing of the superlattice ${\left[{\left({\text{NdMnO}}_3\right)}_5/{\left({\text{SrMnO}}_3\right)}_5/{\left({\text{LaMnO}}_3\right)}_5\right]}_8$. The octahedral structures and spheres represent $B{\text{O}}_6$ and $A$-site atoms in the $AB{\text{O}}_3$ perovskite structure, respectively. The arrays of the arrows represent corresponding antiferromagnetic types. (b) Synchrotron x-ray diffraction for different superlattices. (c) In situ reflection high-energy electron diffraction for the superlattice with $n=5$. (d) The topography image of atomic force microscopy for the superlattice with $n=5$.

Figure 2

(Color) (a) Temperature dependence of the magnetization measured in a magnetic field of 0.1 T applied parallel to the plane of the films. (b) Hysteresis loops obtained at 10 K with a magnetic field applied parallel to the plane of the films.

Figure 3

(Color) Magnetic susceptibility $\left(\chi \right)$ for magnetic fields from 0.05 T to 1.5 T for the sample with $n=2$. The dashed and solid lines depict the susceptibility obtained with ZFC and FC conditions, respectively. (Inset) Spin glass scaling for the superlattice with $n=2$.

Figure 4

(Color) Time response of the magnetization for $\left[{\left({\text{NdMnO}}_3\right)}_2/{\left({\text{SrMnO}}_3\right)}_2/{\left({\text{LaMnO}}_3\right)}_2\right]$. (a) The relaxation of the magnetization is measured at 10 K after cooling in a magnetic field of 0.1 T applied parallel to the plane of the film. The solid line is a fit to $M\left(t\right)=M_0\text{exp}\left[-\alpha {\left(t/{\tau }_0\right)}^{1-y}/\left(1-y\right)\right]$ (b) The increase in the magnetization is measured at 10 K in a field of 0.1 T applied parallel to the film’s plane after cooling in zero field. The solid line is a fit to $M\left(t\right)=M_0+S\text{ln}\left(t+t_0\right)$.

Figure 5

(Color online) (a) PNR measurements for the sample with $n=12$ taken at 300 K (above $T_c$). The orange (gray), green (very light gray), and blue (light gray) regions depict the regions of ${\text{NdMnO}}_3$ (N), ${\text{SrMnO}}_3$ (S), and ${\text{LaMnO}}_3$ (L) layers, respectively. The solid line is a fit of the calculated reflectivity obtained using the SLD model. (b) PNR taken at 10 K (below $T_c$) in 0.6 T after field cooling in the same field. The red (upper) and green (lower) circles are the ${\text{R}}^{+}$ and ${\text{R}}^{-}$ data, respectively. (Inset) The magnetic structure obtained from a calculation which reproduce the PNR data as represented with the solid lines.