Renormalized Field Theory of Amorphous Magnets. I : Stability of Fixed Points in the Magnetic System with Random Easy Axes and Random Exchange Interactions

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概要

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• Critical phenomena of amorphous magnets with N order parameters are studied via the renormalized field theory and the replica method. Investigated model has amorphous properties only for N≧2 and consists of two terms: the random exchange interactions and a term realizing random easy axes. Three coupling constants and two critical indices η and ν are calculated up to O(ε^2)[ε=4-d(d: space dimensionality)]. A fixed point of O(√<ε>) for N=1(Ising) agrees with the stable Khmel'nitzkii fixed point. In the case N=2(XY) or N=3(Heisenberg), there is no stable fixed point, so that no second-order phase transition occurs. For N>N_C=3.9123+(0.57±0.03)ε, one more stable (although unphysical) fixed point emerges. In the limit N→∞, random easy axes give no change unless the intensity of random easy axes increases by the same power of N as N→∞. It is also pointed out that obtained β functions are applicable to the two-loop calculations for the problem of the non-Abelian gauge field with scalar coupling (Higgs model).

• 理論物理学刊行会の論文
• 1983-12-25

著者

• Oku Michiyoshi

  Department Of Pure And Applied Science University Of Tokyo

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