TEMPERATURE-DEPENDENT RUDERMAN-KITTEL-KASUYA-YOSIDA INTERACTION

We develop a method that provides an analytical expression of the free-electron spin susceptibility for arbitrary temperature. The result can be further reduced by using the low-temperature approximation, which shows that the oscillation decays exponentially as exp(-TkFr) in the long-range limit, and the wave number of the oscillation varies as k0kF[1-(2/12)T2], where T is the normalized temperature with respect to the Fermi energy. The result contradicts what Darby has proposed, especially in the long-range region. On the other hand, in the short-range region, where the Sommerfeld expansion method is valid, numerical study shows that Darbys result agrees with ours fairly well. © 1995 The American Physical Society.