Spin frustration of a spin-1/2 Ising–Heisenberg three-leg tube as an indispensable ground for thermal entanglement

Abstract

The spin-1/2 Ising-Heisenberg three-leg tube composed of the Heisenberg spin triangles mutually coupled through the Ising inter-triangle interaction is exactly solved in a zero magnetic field. By making use of the local conservation for the total spin on each Heisenberg spin triangle the model can be rigorously mapped onto a classical composite spin-chain model, which is subsequently exactly treated through the transfer-matrix method. The ground-state phase diagram, correlation functions, concurrence, Bell function, entropy and specific heat are examined in detail. It is shown that the spin frustration represents an indispensable ground for a thermal entanglement, which is quantified with the help of concurrence. The specific heat displays diverse temperature dependences, which may include a sharp low-temperature peak mimicking a temperature-driven first-order phase transition. It is convincingly evidenced that this anomalous peak originates from massive thermal excitations from the doubly degenerate ground state towards an excited state with a high macroscopic degeneracy due to chiral degrees of freedom of the Heisenberg spin triangles.

Quasi-phases and pseudo-transitions in one-dimensional models with nearest neighbor interactions

“…While for specific heat and magnetic susceptibility it exhibits an extremely sharp peak indicating a "pseudo-transition" between the quasi-phases, this pseudo-transition closely resembles a typical second-order phase transition. Some evidence of quasi-phase and pseudo-transitions have already been manifested in recent previous works, such as Ising-XYZ diamond chain [16], tetrahedral chain [17], Ising-Heisenberg ladder model [18], Ising-Heisenberg triangular tube models [19]. However, here we present a general condition for appearing this quasi-phases and pseudo-transitions.…”

“…Indeed, some evidence of this behavior has already been observed in previous work [17][18][19][20], and spin-ice model with shortrange interaction in the Bethe-Peierls approach [20]. The entropy behavior reveals the similarity with the firstorder phase transition [21], so it is interesting to define the "latent heat" associated with the system in T p as…”

“…However, there are some particular models [16][17][18][19] that satisfy the following condition w 0 ∼ w 2 ≫ w 1 and |w 0 − w 2 | ≫ 2w 1 . The free energy using the Taylor series expansion around…”

“…Lately, several one-dimensional models have been investigated in the framework of decorated structures, particularly Ising and Heisenberg models with a variety of structures, such as the Ising-Heisenberg models in diamond chain structure [15,16] as shown in fig.1a, one-dimensional double-tetrahedral chain (see fig.1b), in which the localized Ising spin regularly alternates with two mobile electrons delocalized over a triangular plaquette [17], alternating Ising-Heisenberg ladder model [18], Ising-Heisenberg triangular tube model [19]. * Electronic address: ors@dfi.ufla.br…”

Magnetic and thermodynamic properties of the octanuclear nickel phosphonate-based cage

“…Low-dimensional quantum systems with competing interactions and geometrical frustration are of continued interest in condensed matter physics, material science and chemistry [1,2,3,4,5]. The interest in the magnetic and thermal properties of metal-containing compounds of this type stem not least from their manifestation of various ground-state phase diagrams at zero and low temperatures [5,6,7,8,9,10,11,12,13]. For instance, experimental investigations into the nickel homometallic magnetic compound [Ni 3 (fum) 2 (µ 3 − OH) 2 (H 2 O) 4 ] n · (2H 2 O) n indicate the coexistence of both antiferromagnetic and ferromagnetic interactions [14].…”