Magnon orbital angular momentum of ferromagnetic honeycomb and zigzag lattice models

By expanding the gauge lambda(n)(k ) for magnon band n in harmonics of momentum k =(k ,phi ) , we demonstrate that the only observable component of the magnon orbital angular momentum O-n(k ) is its angular average over all angles phi , denoted by F-n(k ) . Although F-n(k ) vanishes for antiferromagnetic honeycomb and zigzag (0 6 but is still about four times smaller than that of the FM honeycomb lattice at high temperatures. Due to the removal of band degeneracies, kappa(x y)(T ) is slightly enhanced when J(1 y)not equal J(1 x) .