2006/08/31 by Kouji Segawa, Yoichi Ando · 4 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Magnetic and transport properties of perovskites and related materials #Physics of Superconductivity and Magnetism #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.74.100508
published as Phys. Rev. B 74, 100508 (2006) · 4 pages, 4 figures, 1 table, accepted for publication in Phys. Rev. B
arxiv created 2006/09/12 · openalex publication_date 2006/09/29 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Thus far, there is no cuprate system where both n-type and p-type charge carriers can be doped without changing the crystallographic structure. For studying the electron-hole symmetry in an identical structure, we try to dope n-type carriers to YBa2Cu3Oy system by reducing oxygen content and substituting La3+ ions for Ba2+. Single crystals of La-doped YBa2Cu3Oy are grown by a flux method with Y2O3 crucibles and it is confirmed that La actually substitutes \ensuremath∼13% of Ba. The oxygen content y can be varied between 6.21 and 6.95 by annealing the crystals in an atmosphere with controlled oxygen partial pressure. The in-plane resistivity \ensuremathρab at room temperature was found to increase with decreasing oxygen content y down to 6.32, but interestingly further decrease in y results in a decrease in \ensuremathρab. The most reduced samples with y=6.21 show \ensuremathρab of \ensuremath∼30\phantom\rule0.3em0exm\ensuremathΩ\phantom\rule0.2em0excm at room temperature, which is as much as seven orders of magnitude smaller than the maximum value at y=6.32. Furthermore, both the Hall coefficient and the Seebeck coefficient of the y=6.21 samples are found to be negative at room temperatures. The present results demonstrate that the nondoped Mott-insulating state has been crossed upon reducing y and n-type carriers are successfully doped in this material.