Magnetic and Critical Properties of Alternating Spin Chain withS=1/2, 1in Magnetic Fields

Abstract
We study an integrable spin chain with an alternating array of spins S =1/2, 1 in external magnetic fields using the Bethe ansatz exact solution. The calculated magnetization curve has a cusp at a critical magnetic field H = H C , at which the specific heat shows a divergence property. We also calculate finite-size corrections to the energy spectrum, and obtain the critical exponents of correlation functions using conformal field theory (CFT). Low-energy properties of the model are described by two c =1 U (1) CFTs at H < H C and one c =1 U (1) CFT at H > H C .
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