Exact excitation structure of a trimerized S=1/2 XY spin chain, where the ferro- antiferro-antiferromagnetic bonds are dispaced alternately, is calculated by using the Jordan-Wigner fermionic transformation. The anisotropy in the coupling bonds causes...
Exact excitation structure of a trimerized S=1/2 XY spin chain, where the ferro- antiferro-antiferromagnetic bonds are dispaced alternately, is calculated by using the Jordan-Wigner fermionic transformation. The anisotropy in the coupling bonds causes the band gaps among the excitation modes.