Aspect of Spin-Charge Separation Due to Antiferromagnetic Spin Fluctuations in Technically Nested 2D Metals

It is shown that the charge susceptibility in nearly half-filled two-dimensional (2D) metals, with technically nested Fermi surface, shows anomaly at the wave vector different from that for the spin susceptibility at low temperatures. Namely charge degrees of freedom behave there as if their “Fermi surface” corresponded to that of “holes” created in the Mott insulator. Such anomaly is caused by the Aslamazov-Larkin-type contribution of 2D antiferromagnetic spin fluctuations. This phenomenon gives a possible clue to resolve the paradox of normal state properties of high- T c cuprates starting from the Fermi-liquid fixed point.