Figure 3.
Correlated magnetic and Raman measurements of La2PrNi2O7 under pressure. (a) Fluorescence image of sample B (La2PrNi2O7 in KBr). The edge of the sample is outlined with a black dashed line. (b) Magnetic field mapping under an external magnetic field of HZ = 34 G after ZFC of the sample to 7 K. The blue region exhibits a noticeable diamagnetism. In situ Raman measurements are performed on the superconducting regions (B1, B2) and the non-superconducting regions (B3, B5) under different pressures. (c) Magnetic field mapping of one of the superconducting regions [position of purple square marked in (b)] during the FW process; the external magnetic field is around 120 G. Above the critical temperature Tc, the local diamagnetism disappears and all NV centers feel the uniform external magnetic field. The region on the gray square shows a feeble contrast to fit the ODMR splitting. (d) The Raman spectra of B1 and B3 at 20 GPa. As shown in the figure, a small satellite peak is observed in the non-superconducting region (B3) at 20 GPa, while it is suppressed in the superconducting region (B1). This peak is also presented at atmospheric pressure before compression (shown in Fig. S6a).