Magnetism in spin crossover systems: short-range order and effects beyond the Heisenberg model

Abstract

To study non-Heisenberg effects in the vicinity of spin crossover in strongly correlated electron systems we derive an effective low-energy Hamiltonian for the two-band Kanamori model. It contains Heisenberg high-spin term proportional to exchange constant as well as low-spin term proportional to spin gap parameter ${\epsilon }_s$. Using cluster mean field theory we obtain several non-Heisenberg effects. Near critical value of spin gap ${\epsilon }_s^c$ there is a magnetic phase transition of first order. In the vicinity of ${\epsilon }_s^c$ in the paramagnetic phase we observe non trivial behavior of the Curie constant in the paramagnetic susceptibility in the wide range of temperature. Reentrant temperature behavior of nearest-neighbor spin-spin correlations is observed at ${\epsilon }_s>{\epsilon }_s^c$. Finally, pressure-temperature magnetic phase diagram for ferroperriclase is obtained using the effective Hamiltonian.

11 pages, 10 figures

References in corpus (28)

• Neel Temperature of Quasi-Low-Dimensional Heisenberg Antiferromagnets
• High-spin to low-spin and orbital polarization transitions in multiorbital Mott systems
• Phase Diagram of a Frustrated Quantum Antiferromagnet on the Honeycomb Lattice: Magnetic Order versus Valence-Bond Crystal formation
• Anomalous compressibility of ferropericlase throughout the iron spin crossover
• Simple Two-Dimensional Model for the Elastic Origin of Cooperativity among Spin States of Spin-Crossover Complexes
• Realization of the mean-field universality class in spin-crossover materials
• Monte Carlo simulation of pressure-induced phase transitions in spin-crossover materials
• Excitonic condensation in systems of strongly correlated electrons
• A new hybrid LDA and Generalized Tight-Binding method for the electronic structure calculations of strongly correlated electron systems
• Phase diagram and spin correlations of the Kitaev-Heisenberg model: Importance of quantum effects
• Excitonic Instability at the Spin-State Transition in the Two-Band Hubbard Model
• Phase diagram and collective excitation in excitonic insulator: from the orbital physics viewpoint
• Green's-function theory of the Heisenberg ferromagnet in a magnetic field
• Roles of Hund's rule coupling in excitonic density-wave states
• Noncollinear Magnetic Order Stabilized by Entangled Spin-Orbital Fluctuations
• Phase separation in doped systems with spin-state transitions
• Excitonic order at strong-coupling: pseudo-spins, doping, and ferromagnetism
• Spin-state transition and phase separation in multi-orbital Hubbard model
• Entangled spin-orbital phases in the bilayer Kugel-Khomskii model
• Thermodynamics of layered Heisenberg magnets with arbitrary spin
• In-gap excitation effect on a superexchange in La2CuO4 by creating nonequilibrium photoexcited centers
• Loop algorithm for Heisenberg models with biquadratic interaction and phase transitions in two dimensions
• Ground-state phase diagram of the Kitaev-Heisenberg model on a kagome lattice
• Cluster mean field study of the Heisenberg model for CuInVO${}_5$
• The N-Leg spin-S Heisenberg ladders: A DMRG study
• Cooperative Phenomena in Spin Crossover Systems
• Reentrant magnetic ordering and percolation in a spin-crossover system
• Molecular Dynamics of Spin Crossover: the (P,T) phase diagram of [Fe(PM-BIA)2(NCS)2]