用变分累积展开方法计算磁性薄膜的临界指数γ(L)与β(L)

CALCULATION OF CRITICAL EXPONENTS γ(L) AND β(L) FOR MAGNETIC THIN FILMS USING VARIATIONAL CUMULANT EXPANSION

Lin Douliang等人把变分累积开展 ( VCE)方法用于薄膜 ,计算了各种结构的磁性薄膜的临界温度[1 ,2 ] .本文是文献 [1 ]的继续 ,计算了 L层磁性薄膜的临界指数 γ( L)与 β( L) ,计算结果与文献 [3～ 5]的实验结果符合 .对于 L=1 (相当于 2维 )这一特例 ,我们的计算结果与精确解符合得相当好 .

Critical temperature for magnetic films with various lattice structures has been calculated by means of variational cumulant expansion (VCE) methad [1,2] . In this paper, the critical exponents γ(L) and β(L) for the magnetic films up to L layers using VCE on the basis of the reference[1]are calculated and the theoretical results presented here are in agreement with the experimental results given in references[3~5]. For special case of L=1 (two dimensional case), the result obtained is nearly coincidence with the solution by means of other higher accuracy approaches.