Investigation of the magnetic phase diagram of the 2D ferrimagnetic J ₁–J ₂ model

Abstract

The zero-temperature phase diagram and spin dynamics of the 2D ferrimagnetic J 1–J 2 model with (S 1, S 2) = (1/2, 1) are investigated using the time-dependent cluster mean-field theory (t-CMFT). The t-CMFT enables the investigation of the quantum-mechanical as well as semi-classical phase diagram and spin dynamics by control of the entanglement. For the characterization of the ferrimagnetic system, the magnetization, the energy per atom, the cluster quantum states and the von Neumann entropy have been determined.

Investigation of the temperature phase diagram of the 2D semi-classical ferrimagnetic J1−J2 model

“…Then, it remains to be clarified what is meant by the semi-classical limit. In the case of the quantum mechanical description of ferrimagnets, entanglement plays an important role [40,45]. In general, most spin states are entangled.…”

“…More than 100 publications have been published about this system. While the antiferromagnetic J 1 −J 2 model has received much attention, the ferrimagnetic J 1 −J 2 model has received almost no attention [35][36][37][38][39][40]. The ferrimagnetic J 1 −J 2 model is far more interesting than the antiferromagnetic J 1 −J 2 model.…”

“…The ferrimagnetic J 1 −J 2 model is far more interesting than the antiferromagnetic J 1 −J 2 model. The reason is that there are effective three exchange interactions in the ferrimagnetic J 1 −J 2 model with a checkerboard-like arrangement of the two spin varieties [37,40]. The nearest neighbor exchange interaction J 1 is between the two different spin types (inter sublattice interaction).…”

“…This inequality in the next-nearest neighbor exchange interactions leads to a non-collinear state. A detailed description of the quantum mechanical ferrimagnetic J 1 −J 2 Heisenberg model and its semiclassical limit at zero temperature has been given in [40]. This publication extends the phase diagram by taking the temperature into account.…”

“…Previous publications [37,40] have investigated the effect of frustration in the ferrimagnetic J 1 −J 2 model. For this purpose, the strength of the next-neighbor exchange interaction J 2 was systematically changed, and the zero-temperature phase diagram was investigated.…”