Magnetic and critical properties of alternating spin chain with S=1/2, 1 in magnetic fields

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.