Quantum phase transition and magnetic plateau in three-leg antiferromagnetic Heisenberg spin ladder with unequal J1–J2–J1 legs

Abstract Magnetic properties of spin-1/2 antiferromagnetic three-leg Heisenberg ladders, where antiferromagnetic interactions in legs are J 1 , J 2 and J 1 respectively and in the rungs are J ⊥ , have been investigated by bond-mean field method. As J ⊥ changes, magnetization curves show different behavior. For J ⊥ =0.5, there are cusps in magnetization curves, while for J ⊥ =3.0, the 1/3 magnetization plateau appears, which can be explained by energy spectra. Furthermore, for J ⊥ =3.0 the 1/3 magnetization plateaus will become wider or narrow down with J 2 changing. In addition, the mean-field bond parameters and the concurrences, which confirm the phase transitions, are also studied.