Quantum Magnetism in Fe2Cu2 Polymeric Branched Chains: Insights from Exactly Solved Ising-Heisenberg Model

Abstract

The spin-1/2 Ising-Heisenberg branched chain, inspired by the magnetic structure of three isostructural polymeric coordination compounds [(Tp)2Fe2(CN)6X(bdmap)Cu2(H2O)].H2O to be further denoted as Fe2Cu2 (Tp = tris(pyrazolyl)hydroborate, bdmapH = 1,3-bis(dimethylamino)-2-propanol, HX = acetic acid, propionic acid or trifluoroacetic acid), is rigorously studied using the transfer-matrix method. The overall ground-state phase diagram reveals three distinct phases: a quantum antiferromagnetic phase, a quantum ferrimagnetic phase and a classical ferromagnetic phase. In the zero-temperature magnetization curve, two quantum ground states are manifested as intermediate plateaus at zero and half of the saturation magnetization, while the magnetization reaches its saturated value within the classical ferromagnetic phase. The bipartite entanglement between nearest-neighbor Heisenberg spins is more pronounced in the quantum ferrimagnetic phase compared to the quantum antiferromagnetic phase due to a fully polarized nature of the Ising spins. A reasonable agreement between theoretical predictions for the spin-1/2 Ising-Heisenberg branched chain and experimental data measured for a temperature dependence of the magnetic susceptibility and a low-temperature magnetization curve suggests strong antiferromagnetic coupling between nearest-neighbor CuII-CuII magnetic ions and moderately strong ferromagnetic coupling between nearest-neighbor CuII-FeIII magnetic ions in the polymeric compounds Fe2Cu2. A thermal entanglement between nearest-neighbor CuII-CuII magnetic ions persists up to a relatively high threshold temperature T = 224 K and undergoes a transient magnetic-field-driven strengthening.

20 pages, 9 figures

References in corpus (6)

• Geometric frustration in the class of exactly solvable Ising-Heisenberg diamond chains
• Dysprosium-based experimental representatives of an Ising-Heisenberg chain and a decorated Ising ring
• Entangled state teleportation through a couple of quantum channels composed of XXZ dimers in an Ising-XXZ diamond chain
• Ferrimagnetic spin-1/2 chain of alternating Ising and Heisenberg spins in arbitrarily oriented magnetic field
• Insight into ground-state spin arrangement and bipartite entanglement of the polymeric coordination compound [Dy${}_2$Cu${}_2$]${}_n$ through the symmetric spin-1/2 Ising-Heisenberg orthogonal-dimer chain
• Spotlighting quantum phase transition in spin-1/2 Ising-Heisenberg diamond chain employing Measurement-Induced Nonlocality