Pressure-induced tuning of a magnetic phase separation in Nd${}_{0.53}$Sr${}_{0.47}$MnO${}_3$

X-ray magnetic circular dichroism and neutron diffraction measurements were conducted in situ at high pressure and low temperature to investigate the evolution of the magnetic properties of Nd${}_{0.53}$Sr${}_{0.47}$MnO${}_3$ (NSMO47). The neutron diffraction data provide the experimental evidence for the presence of antiferromagnetic domains within the conducting ferromagnetic host at ambient pressure. The antiferromagnetic phase becomes dominant above 3 GPa with a concomitant reduction of the FM phase. Those findings indicate that the magnetic ground state of NSMO47 is more complex than previously reported, confirming the coexistence of competing phases over the doping range in which colossal magnetoresistance is observed. We also find that magnetic phase separation in the form of domains appears to be an intrinsic phenomenon at high pressure.

Figure 1

(a) Temperature dependence of Mn $K$ (blue starts) and Nd $L_3$ XMCD (black circles) signals collected at ambient pressure. Results obtained performing SQUID magnetization measurements (red squares) are superimposed to the XMCD data. (Inset) Temperature dependence of the Nd $L_3$ XMCD signal at 8.6 GPa, obtained performing XMCD measurements decreasing temperature. (b) Normalized XMCD data at low temperature and different pressures. The data at 4 GPa were collected on decreasing pressure.

Figure 2

Low $d$-spacing neutron diffraction patterns collected at 88 K as a function of pressure. The asterisks indicate peaks from NaCl. The (2 0 2)/(0 2 2) NSMO47, the (2 0 0) NaCl, and the (1 1 1) pure magnetic peaks are indicated. (Left inset) Rietveld refinement of the neutron pattern collected at ambient pressure and low temperature. (Right inset) Neutron diffraction patterns collected at 300 and 88 K at ambient pressure; the black arrow indicates the pure magnetic peak (1 1 1) centered at 3.43 Å.

Figure 3

Rietveld refinement of the high $d$-spacing neutron pattern collected at ambient pressure and 88 K. (Inset) High $d$-spacing neutron diffraction patterns collected at 88 K at different pressures. The broad shoulder observed around $d=7\AA$ is a background distortion.

Figure 4

(a) Pressure evolution of the normalized XMCD integrated intensities. The pressure point at 4 GPa was collected decreasing pressure. Pressure dependence of (b) lattice parameters and (c) orthorhombic distortion. (d) Evolution of the FM and AFM effective magnetic moments with pressure. Dashed curves are guides for the eye.