Magnetic anisotropy in inverse-sandwiched iridium-boron clusters: Single-molecule magnets from first-principles

Magnetic anisotropy is a key physical parameter for the miniaturization of magnetic information storage, and developing nanomaterials with high magnetic anisotropy is of high significance to magnetic storage technology. Among them, single-molecule magnets (SMMs) are of interest for high-density magnetic storage. Here, using first-principles calculations, we designed a series of Ir2Bnq (n = 6–10, q = 0, ±1) clusters featuring inverse sandwich structures and identified Ir2B8 to be the global minimum. As a stable and aromatic SMM, the inverse-sandwiched Ir2B8 carries a magnetic anisotropy energy (MAE) of 93.43 meV. By taking the advantage of Ir2 symmetrically locked on two sides B8 ring and the lowest energy in the inverse sandwich structure of Ir2B8, the high MAE can be maintained at high temperature as 700 K. In contrast to the reported Ir2 loaded on one side of a two-dimensional molecule/material, the direction of Ir2 is prone to be tilted with physical perturbation and the MAE could not be well preserved. Furthermore, when Ir2B8 is encapsulated in two different carbon nanotubes, the high MAE could be well preserved (97.10 meV) or even enlarged (145.50 meV). This work establishes a unique framework for designing high-temperature stable SMMs with superior performance.