Superconductivity and Pseudogap in Quasi-Two-Dimensional Metals around the Antiferromagnetic Quantum Critical Point(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

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Spin fluctuations (SF) and SF-mediated superconductivity (SC) in quasi-two-dimensional metals around the antiferrromagnetic (AF) quantum critical point (QCP) are investigated by using the self-consistent renormalization theory for SF and the strong coupling theory for SC. We introduce a parameter y_0 as a measure for the distance from the AFQCP which is approximately proportional to (x-x_c), x being the electron (e) or hole (h) doping concentration to the half-filled band and x_c being the value at the AFQCP. We present phase diagrams in the T-y_0 plane including contour maps of the AF correlation length and AF and SC transition temperatures T_N and T_c, respectively. The T_c curve is dome-shaped with a maximum at around the AFQCP. The calculated one-electron spectral density shows a pseudogap in the high-density-of-states region near (π, 0) below around a certain temperature T^* and gives a contour map at the Fermi energy reminiscent of the Fermi arc. These results are discussed in comparison with e- and h-doped high-T_c cuprates.
社団法人日本物理学会の論文
2009-01-15