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 possesses a cusp structure 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 with the use of conformal field theory (CFT). Low-energy properties of the model are described by two c=1 U(1) CFTs in H<H_{C} and one c=1 U(1) CFT in H>H_{C}. 
Mitsuru Fujii (1), Satoshi Fujimoto (2) and Norio Kawakami (1) ((1)   Department of Applied Physics, Osaka University (2) De...