@article{oai:niigata-u.repo.nii.ac.jp:00002129, author = {Sano, Kazuhiro and Ono, Yoshiaki}, issue = {11}, journal = {Journal of the Physical Society of Japan, Journal of the Physical Society of Japan}, month = {Nov}, note = {Using the numerical diagonalization method, we examine the one-dimensional t1-t2-J1-J2 model (zigzag chain t-J model) which represents an effective model for metallic CuO double chain in the superconductor Pr2Ba4Cu7O15-δ. Based on the Tomonaga-Luttinger liquid theory, we calculate the Luttinger-liquid parameter Kp as a function of electron density n. It is found that superconductivity is realized in parameter region corresponding to the experimental result. We show phase diagram of spin gap on the t2/|t1|-n plane by analyzing the expectation value of twist-operator Zσ in the spin sector. The spin gap appears in the region with large t2/|t1|, where the phase boundary at half-filling is consistent with that of the known frustrated quantum spin system. The analysis also suggests that the estimated value of the spin gap reaches 100 K in the realistic parameter region of Pr2Ba4Cu7O15-δ.}, pages = {113701-1--113701-4}, title = {Superconductivity and Spin gap in the zigzag chain t-J model simulating a CuO double chain in Pr2Ba4Cu7O15-δ}, volume = {76}, year = {2007} }