Elastic frustration and multi-stability in 1D spin-crossover chains: A homogeneous electro-elastic approach

This study investigates the thermal and spatiotemporal properties of a one-dimensional (1D) spin-crossover monoatomic chain using a homogeneous version of the electro-elastic model. This framework maps the original system initially defined by two degrees of freedom (atomic positions and spins) onto an effective Ising-like model. The resulting formulation combines infinite long-range ferroelastic interactions with short-range anti-ferroelastic interactions between nearest-neighbor and next-nearest-neighbor sites. The analytical treatment of this mapping enables the identification of all interaction parameters within the Ising-like model and establishes their direct physical relationship with the original elastic parameters. Consequently, this approach avoids the reliance on purely phenomenological interaction parameters commonly found in standard Ising-like models for spin transitions. The obtained results demonstrate the power of the present formalism and the key role of elastic frustration in stabilizing multi-step transitions in 1D spin-crossover materials.