Roles of Mott physics in Semiconductor Impurity Bands and Copper-Oxide Superconductors

09 June 2010 (Wed) 3:30 pm - 5:00 pm

8F large seminar room, SENGEN site

Prof. Hiroshi Kamimura (上村洸 教授)

Tokyo University of Science (東京理科大学)

Roles of Mott physics in Semiconductor Impurity Bands and Copper-Oxide Superconductors

In this talk, I would like to propose that Mott physics due to electron-electron interactions plays a similar role in semiconductor impurity bands and copper oxide superconductors. In the impurity bands in doped semiconductors the interplay of disorder and electron-electron (e-e) interactions gives rise to the coexistence of spin-singlet and spin-triplet states in the strongly Anderson-localized regime just below the metal-insulator transition. As a result peculiar spin-dependent phenomena appear in various physical properties of doped semiconductors, such as specific heat, spin susceptibility, and magnetoresistance in the Anderson-localized regime.

In copper oxide (cuprate) superconductors, on the other hand, the interplay of Jahn-Teller Physics and Mott Physics plays important roles in giving rise to the coexistence of a metallic state and the local antiforromagnetic (AF) order. As a result the feature of Fermi surface in cuprates is the occurrences of Fermi-pockets constructed from the doped holes without the pseudogap hypothesis. In the second part of the present talk I will discuss why cuprates show Fermi pockets rather than a large Fermi surface with the pseudogap. This theoretical result will be compared with recent experimental results of angle-resolver photoemission spectroscopy (ARPES) in cuprates both below and above Tc.

Dr. Takahisa Ohno(大野　隆央)