Multi-Step in 3D Spin Crossover Nanoparticles Simulated by an Ising Model Using Entropic Sampling Monte Carlo Technique

Abstract

There are currently extended experimental and theoretical developments of spin crossover nanomaterials, in particular based on coordination polymers for the design of smart applications. In this context, we have reproduced a three step thermal transition in a cubic spin crossover nanomaterial with a system dimension of 5ˆ5ˆ5 metallic centers. For this purpose, we have calculated, using Monte Carlo Entropic Sampling technique, the density of states of all possible system configurations. In order to take into account the local environment, we have included an additional interaction term in the standard Ising like model. We have then analyzed the role of this new interaction as well as the system size effect variation (from 4ˆ4ˆ4 to 6ˆ6ˆ6 metallic centers). Comparison with a 2D SCO system shows that the spin transition still proceeds in three steps but is no longer hysteretic.

Three Stable States Simulated for 1D Spin‐Crossover Nanoparticles Using the Ising‐Like Model

“…With these contributions, the Hamiltonian now includes the short‐ and long‐range interactions, to which we added an energetic contribution ( L ) to the ligand field of the edge molecules of an SCO nanoparticle . This term allows us to take into account explicitly the interactions between molecules on the edge and the environment in close contact, which weaken the molecular field.…”

“…A new challenging problem related to SCO nanoparticles at the nanoscale level has also been highlighted recently. The problem is connected to the particle size, which plays an important role in the cooperativity of the nanosystem, in particular, the role of edge molecules.…”

Magnetoelastic modeling of core-shell spin-crossover nanocomposites

“…They have been studied [1][2][3][4][5][6][7][8][9]f o r many years for their promising applications as sensors of pressure [10], displays [11], memories, and molecular switches [12]. During the last decade, compounds with multistep spin conversion remained quite rare and have attracted increasing attention in theoretical and experimental studies [13][14][15][16][17], due to their possibility to build up three-byte electronics.…”

“…Indeed, most of the experimental studies on SCO nanoparticles, if not all, have been realized on a large number of nanoparticles. Thus, for example, when Mossbauer spectroscopy studies (where around 20 mg of sample are necessary) are performed on SCO nanoparticles (average density ∼2g/cm 3 )i ti se a s yt o evaluate their number at a minimum is around ∼10 15 , which then lead to obtaining an averaged response over nanoparticles with different size, shapes, surface structures, etc. In short, as long as experimental studies on one single nanoparticle, like in magnetic systems [76,77], are not realized, this issue will not be definitely resolved.…”

Special Issue “Spin Crossover (SCO) Research”

“…Following the announced spirit of the original call, very diverse aspects of the phenomenon of spin transition are treated. Therefore, a good balance between theory, synthesis, and physical studies is encountered, while various manifestations of SCO materials are present as part of the theoretical treatments as well as experimentally (molecular, polymeric, nano-structured, and composite materials).The issue includes Monte Carlo simulations of the dynamic properties of the SCO phenomenon analyzing the influence of crystal defects [1], the surface effects [2], and the interactions within the bulk of the system using an Ising model [3]. In addition, density functional theory (DFT) calculations are employed to study the cooperativity using a very well-known experimental compound [4].…”