Transport properties of Pr$_{2}$Ba$_{4}$Cu$_{7}$O$_{15-\delta}$ under high pressures

Pr$_{2}$Ba$_{4}$Cu$_{7}$O$_{15-\delta}$ (Pr247) was found to exhibit superconductivity in 2004 by introducing oxygen deficiencies.\footnote{Matsukawa et al., Physica C, 411,101(2004).} Superconducting transition temperature (T$_{\mbox{c}}$) varies from zero to about 20 K depending on the oxygen deficiency $\delta$. This high-T$_{\mbox{c}}$ cuprate consists of three structural units, i.e., CuO$_{2}$ planes, CuO single chain and CuO double chains. The CuO$_{2}$ planes are insulating in this compound and therefore, the superconductivity is believed to occur in the CuO double chains. Interestingly, the electrical resistivity was found to show T$^\alpha$ dependence at low temperatures under high magnetic fields.\footnote{Matsushita et al., Sci. Tech. Adv. Mater., 8,477(2007).} This temperature dependence is known as the characteristic property of Tomonaga-Luttinger liquid and suggests a possibility that the CuO double chains have one-dimensional property. In this study we report the pressure dependence of the transport properties for Pr247 with various oxygen deficiency $\delta$'s.