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Thermal entanglement of the spin-1 Ising–Heisenberg diamond chain with biquadratic interaction

We investigate the thermal entanglement of the spin-1 Ising–Heisenberg diamond chain, which can be regarded as a theoretical model for the homometallic molecular ferrimagnet [Ni3(C4H2O4)2−(μ3−OH)2(H2O)4]n·(2H2O)n. Two cases, i.e., the isotropic Heisenberg (Ising–XXX) coupling model and anisotropic Heisenberg (Ising–XXZ) coupling model, are discussed respectively. The negativity is chosen as the measurement of the thermal entanglement. By means of the transfer-matrix approach, we focus on the effects of biquadratic interaction parameters on the negativity of the infinite spin-1 Ising–Heisenberg diamond chain. In the Ising–XXX coupling model, it is shown that for the case with ferromagnetic coupling the thermal entanglement can be induced by the biquadratic interaction, but the external magnetic field will suppress the occurrence of the entanglement induced by the biquadratic interaction. In the Ising–XXZ coupling model, for the case with antiferromagnetic coupling, due to the biquadratic interaction the effect of the anisotropy parameter on the entanglement will be suppressed at near-zero temperature. Moreover, the biquadratic interaction makes the threshold temperature increase. The effects of the external magnetic field on the thermal entanglement are also discussed, and it is observed that the entanglement revival phenomena exist in both models considered.