Alternating spin chain in a magnetic field

James H. Taylor, Gerhard H. Muller

Wim Magnus, Willy Boon

Mitsuru Fujii, Satoshi Fujimoto, Norio Kawakami

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 HH_{C}.

Oleg Derzhko, Taras Krokhmalskii, Joachim Stolze

Joachim Stolze, Oleg Derzhko, Taras Krokhmalskii

Ryosuke Nakanishi, Takaharu Yamada, Rito Furuchi +5 more

The S = 1/2 ferromagnetic-antiferromagnetic bond-alternating spin chain with the anisotropy on the ferromagnetic exchange interaction in magnetic field is investigated using the numerical diagonalization and the density matrix renormalization group analyses.It is found that the nematic-spin-dominant Tomonaga-Luttinger liquid phase is induced by the external magnetic field for sufficiently large anisotropy.The phase diagram with respect to the anisotropy and the magnetization is presented.