Imaging the First-Order Magnetic Transition in ${\mathrm{La}}_{0.35}{\mathrm{Pr}}_{0.275}{\mathrm{Ca}}_{0.375}{\mathrm{MnO}}_3$

The nature of the ferromagnetic, charge, orbital, and antiferromagnetic order in ${\mathrm{La}}_{0.35}{\mathrm{Pr}}_{0.275}{\mathrm{Ca}}_{0.375}{\mathrm{MnO}}_3$ on the nano- and microscale was investigated by photoemission electron microscopy (PEEM) and resonant elastic soft x-ray scattering (RSXS). The structure of the ferromagnetic domains around the Curie temperature $T_C$ indicates that they nucleate under a high degree of lattice strain, which is brought about by the charge, orbital, and antiferromagnetic order. The combined temperature-dependent PEEM and RSXS measurements suggest that the lattice distortions associated with charge and orbital order are glassy in nature and that phase separation is driven by the interplay between it and the more itinerant charge carriers associated with ferromagnetic metallic order, even well below $T_C$.

Figure 1

(a) The experimental geometry for the RSXS experiments. $\mathbf{k}$ and ${\mathbf{k}}^{\prime }$ are the incoming and outgoing photon wave vectors, respectively. (b) Experimental geometry for PEEM. (c) Momentum scans and (d) XMCD images taken at 170 K (top) and 60 K (bottom).

Figure 2

PEEM data: XMCD images taken while cooling and warming the sample. Inset: The two images on either side of $T_C$, warming, with enhanced contrast to highlight the changes in the domain pattern across $T_C$. 48 K was the lowest temperature that we could achieve.

Figure 3

RSXS data: (a) Integrated RSXS intensity, (b) correlation length, and (c) $q$ of the CO/OO/AF domains. (▴) warming; (▾) cooling from room temperature; (◆) cooling, after warming from 32 K to 150 K. (d) Magnetization determined from XMCD, normalized to the coldest image. Different symbols represent different cooling-warming cycles. Squares represent the images shown in Fig. 2. Dotted vertical lines represent $T_C$ as determined by the RSXS measurements; it is different for each of the three measurement schemes. The gray band represents $T_g$, as the glass transition does not have a sharp onset.