Magnetic Properties Of The David Star In The 2d-Kagome Lattice

We investigate the magnetisation and internal energy of the David star in the Kagome lattice by the effective field theory developed by Kaneyoshi. First-order, Second-order and successive phase transitions are observed for different spin-down orientations. Spin-down orientation of identical atoms causes a second-order phase transition, spin-down orientation of different atoms causes a first-order and successive phase transitions. Minimum internal energy is obtained as U (David star )=( )-5 for all spin-up orientations, whereas it increases (U (David star )> -5) for at least one spin-down orientation. For spin-down orientation of A up arrow-A down arrow, internal energy becomes zero at a certain temperature and we call this temperature 'zero internal energy temperature (Tzie)'. At T < Tzie( )=( )1.99, internal energy is positive, whereas it is negative for other spin states. Therefore, spin-induced minimum internal energy broken is observed except for all spin-up (A up arrow, B up arrow and C up arrow) cases.