Magnetic Properties of The two-leg zig-zag ladder in quantum spin system NH4CuCl3

Teguh Yoga Raksa and Budhy Kurniawan
Jurusan Fisika, FMIPA, Universitas Indonesia, Depok 16424, Indonesiae-mail : teguhyr@scientist.com and bkuru@fisika.ui.ac.id

abstract

Numerical analysis of the two-leg zig-zag ladder as a single chain with next-nearest neighbour interaction interactions has been formulated by Cabra (1999) with Hamiltonian :



other formulation for two leg zig-zag ladder with dimmerized chains and coupling between the chains is as follow :


from these formulations, we study the closing of the gap at zero magnetization by means of the fine –tuning mechanism and disappreance of the ½ plateau (gap) at finite by alternating dimerization of the chains along the rungs. We also described NH4CuCl3 under high magnetic field s in a two-leg system.

Key word : two leg zig-zag ladder, NH4CuCl3, Dimerized chain