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Zero-Doping State and Electron-Hole Asymmetry in an Ambipolar Cuprate



Kouji Segawa, M. Kofu, S.-H. Lee, I. Tsukada, H. Hiraka, M. Fujita, Sung Chang, K Yamada, Yoichi Ando


What exactly happens when a charge carrier is doped into a Mott insulator is a key question in many-body physics, for it lies at the heart of the problem of the high-temperature superconductivity in cuprates. To address this issue, ideally one should start from a zero-doping state and be able to introduce both holes and electrons in the dilute limit. However, such an idealized experiment has been impossible because of the lack of suitable materials. Here we show that a new "ambipolar" cuprate makes it possible for the first time to cross the zero-doping state in the same material, which in turn allows us to address physics of the extremely low doping region. Surprisingly, we found that the antiferromagnetic ground state sharply changes between electron- and hole-doped sides, and this change is dictated by the existence of only 0.1 ppm of charge carriers. Moreover, we observed that the Neel temperature TN shows an unexpected reduction in a narrow range near the zero-doping state and, intriguingly, TN is the highest for »10 ppm of hole doping. Our results indicate that the physics of the low doping region close to the Mott state is more intricate than expected, and call for a theoretical reexamination of the Mott physics.
Nature Physics


Segawa, K. , Kofu, M. , Lee, S. , Tsukada, I. , Hiraka, H. , Fujita, M. , Chang, S. , Yamada, K. and Ando, Y. (2010), Zero-Doping State and Electron-Hole Asymmetry in an Ambipolar Cuprate, Nature Physics, [online], (Accessed April 12, 2024)
Created July 31, 2010, Updated October 12, 2021