On the susceptibility in La2-xSrxCuO4

The magnetic susceptibility chi in La2-xSrxCuO4 shows unusual concentration x- and temperature T-behaviors. The chi at 400 K increases with x in the range 0.04 < x < 0.25 and decreases in the range 0.25 < x < 0.33. The maximum at x = 0.25 is interpreted in terms of the curvature invension of the O-Fermi surface. Rt the inflection point the density of states is extremely high, which causes chi to have a temperature behavior: chi = A(0)+B-0/T. The Cooper pair (pairon) has no net spin, and hence its spin contribution to chi is zero. But its motion with the linear dispersion relation: epsilon = (2/pi)nu (FP), where nu (F) = Fermi speed, can generate a T-dependent contribution -B-1/T. These two contributions generate a chi -maximum at T-m in the range 0.15 < x < 0.25.