*2.1.3 Pressure effect on transport properties of Pr*2*Ba*4*Cu*7*O*<sup>15</sup>*<sup>δ</sup> samples*

It is well known that application of external pressure on oxide superconductors changes doped carrier densities, causing a positive or negative dependence of their


*In details, see the corresponding text and references. δ denotes oxygen deficiency. a Ref. [12].*

### **Table 1.** *Sample details of Pr*2*Ba*4*Cu*7*O*<sup>15</sup>*<sup>δ</sup> used in the experiments.*

*b Ref. [27].* superconducting transition temperature. We carried out the temperature dependence of the resistivity and the magneto-resistance (MR), under a maximum pressure of 2 GPa.

The MR effect of Pr247 sample was measured at low temperatures as a function of applied field up to 14 T using a 15 T-SM superconducting magnet at Institute for Materials Research, Tohoku University. The electric current *I* was excited in the longitudinal direction to the sample and the external magnetic field *H* was applied in the transverse direction to it (*H*⊥*I*). We measured the influence of applied pressure on the electric resistivity using a hybrid piston cylinder-type CuBe/NiCrAl cell under hydrostatic pressure up to 2.0 GPa, where inner and outer cylinders were made of NiCrAl and CuBe alloys, respectively. A mixture of Fluorinert FC-70 and FC77 (1:1) was used as a pressure transmitting medium in the experiments.

### **2.2 Double perovskite photocatalytic semiconductor**
