Spontaneous antiferromagnetic long-range order in the two-dimensional hybrid model of localized Ising spins and itinerant electrons

Abstract

The generalized decoration-iteration transformation is adopted to treat exactly a hybrid model of doubly decorated two-dimensional lattices, which have localized Ising spins at their nodal lattice sites and itinerant electrons delocalized over pairs of decorating sites. Under the assumption of a half filling of each couple of the decorating sites, the investigated model system exhibits a remarkable spontaneous antiferromagnetic longrange order with an obvious quantum reduction in the staggered magnetization. It is shown that the critical temperature of the spontaneously long-range ordered quantum antiferromagnet displays an outstanding nonmonotonic dependence on a ratio between the kinetic term and the Ising-type exchange interaction.

Vigorous thermal excitations in a double-tetrahedral chain of localized Ising spins and mobile electrons mimic a temperature-driven first-order phase transition

“…[8][9][10][11][12] and references therein). However, it has been shown later * Electronic address: galisova.lucia@gmail.com † Electronic address: jozef.strecka@upjs.sk on that this conceptually simple approach is also applicable for spinless fermion models when ignoring the hopping term on particular lattice sites [13,14], or for hybrid spin-electron systems, where finite clusters including a few mobile electrons are mutually inter-connected through the localized Ising spins in order to form either one- [15][16][17][18][19][20][21] or two-dimensional [22][23][24][25] lattice.…”

Effect of On-Site Coulomb Repulsion on Phase Transitions in Exactly Solved Spin-Electron Model

“…Before doing this, however, it is noteworthy that the special case of this hybrid system without the on-site repulsion term has already been examined in detail by present authors in the earlier paper [4]. The exact results for this particular model revealed that the ground state of the system consists of an interesting four-sublattice quantum antiferromagnetic phase |AF .…”

“…1 in Ref. [4]), which have one localized Ising spin at each nodal lattice site and two delocalized mobile electrons at each couple of decorating sites. The total Hamiltonian of the model can be written as a sum over bond HamiltoniansĤ = kĤ k , where each bond HamiltonianĤ k involves all interaction terms of k-th couple of delocalized electronŝ…”

Kinetically-Driven Frustration in Hybrid Spin Ladders

“…In a diamond-like geometry, this class of models displays magnetization plateaus [1] and an enhanced magnetocaloric eect [2]. In a square lattice geometry, the quantum correlations may lead to ferromagnetic [3] or antiferromagnetic [4] ordering depending on the lling fraction of the delocalized orbitals.…”

“…Recently, a new class of hybrid spin systems was introduced with nodal localized Ising spins and interstitial delocalized electrons [1][2][3][4]. In a diamond-like geometry, this class of models displays magnetization plateaus [1] and an enhanced magnetocaloric eect [2].…”