Spin-1/2 Ising\u2013Heisenberg Cairo pentagonal model in the presence of an external magnetic field: effect of Land\ue9 g-factors

Abstract: In the present paper, a study of the magnetic properties of a spin-1/2 Ising\u2013Heisenberg Cairo pentagonal structure is presented. The model has been investigated in [F.C. Rodrigues, S.M. de Souza, O. Rojas, Ann. Phys. 379, 1 (2017)] in the absence of external magnetic field. Here, we consider the effects of an external tunable magnetic field. By using the transfer matrix approach, we investigate the magnetic ground-state phase transition, the low-temperature magnetization process, and how the magnetic field influences the various thermodynamic parameters such as entropy, internal energy and specific heat. It is shown that the model exhibits intermediate magnetization plateaux accompanied by a double-peak in the specific heat curve versus temperature. The position of each magnetization jump is in accordance with the merging and/or separation of the two peaks in the specific heat curve. Considering different g-factors for the nodal Ising spins and spin dimers also results in arising different intermediate plateaux and to remarkable alterations of the thermodynamic properties of the model. Graphical abstract: [Figure not available: see fulltext.]