Size of orbital-ordering domain controlled by the itinerancy of the $3d$ electrons in a manganite thin film

An electronic effect on a macroscopic domain structure is found in a strongly correlated half-doped manganite film ${\text{Nd}}_{0.5}{\text{Sr}}_{0.5}{\text{MnO}}_3$ grown on a (011) surface of ${\text{SrTiO}}_3$. The sample has a high-temperature (HT) phase free from distortion above 180 K and two low-temperature (LT) phases with a large shear-mode strain and a concomitant twin structure. One LT phase has a large itinerancy (A type), and the other has a small itinerancy (CE type), while the lattice distortions they cause are almost equal. Our x-ray diffraction measurement shows that the domain size of the LT phase made by the HT-CE transition is much smaller than that by the HT-A transition, indicating that the difference in domain size is caused by the difference in orbital arrangement and resulting itinerancy of the LT phases.

Figure 1

(Color online) Temperature dependence of the resistivity in various magnetic fields. Solid curves and dashed curves show the results on warming and cooling runs, respectively. Inset: schematic view of high-temperature (HT) phase and two twin-2 structures with shear-mode strain.

Figure 2

(Color online) Intensity profile around 242 Bragg reflection measured at (a) 200 and (b) 10 K. The intensity was normalized so that the integrated intensity is constant when the magnetic field is applied. The inset for panel (b) shows the magnetic field dependence of the peak width of ${\left(242\right)}_{\text{HT}}$ component measured at 10 K with the field-cooled (FC) and zero-field-cooled (ZFC) procedures.

Figure 3

(Color online) Temperature–magnetic field phase diagram for NSMO/STO(011). The magnetic field was parallel to the $\left[11\overline{1}\right]$ or $\left[1\overline{1}1\right]$ direction (depending on the domain). The magnetic field was applied in the FM phase, and transition temperatures were measured in both cooling and warming runs. PS represents the phase segregated state of FM and CE phases.

Figure 4

(Color online) (a) Schematic view of the film at (left) high temperature and (right) low temperature for the cooling field below 4 T; (b) those for the cooling field above 4 T. The actual in-plane LT domain size is larger than 300 nm, the resolution limit of the experiment. (c) Volume fraction of the LT phase estimated by ${\left(224\right)}_{\text{LT}}$ intensity (circles) and the superlattice intensity (squares) measured at 10 K with field cool (open symbols) and zero-field cool (closed symbols) as a function of magnetic field, together with the HT-phase fraction by ${\left(242\right)}_{\text{HT}}$ intensity. Electric resistivity at 10 K in the field cool (open triangles) and zero-field cool (solid lines) is also presented.