Importantly the non-negligible intermolecular magnetic interactions can be modified by changing intermolecular distances, for example, making these distances shorter would be expected to increase the strength of the exchange and increase the ordering temperature, T c (ref.
In these systems, magnetic order originates from the non-colinearity of neighbouring spin centres which are ‘canted’ at a particular angle ( α) with respect to each other 10. Magnetic anisotropy also plays a significant role in spin-canted systems 19, which behave as weak ferromagnets 10. An alternative way of harnessing and exploiting magnetic anisotropy, and other important factors such as the nature and strength of intra- and intermolecular exchange interactions, is through the use of pressure, since the latter can be used to modify intramolecular bond lengths, angles and metal geometries, and important intermolecular interactions such as H-bonds, C–H Here, the physical behaviour is, in part, governed by the magnetic anisotropy of the molecule, which in turn originates from symmetry and structure-factors that are a challenge to control via synthetic chemistry. The synthesis of molecules whose behaviour resembles that of classical bulk magnets has been an important challenge for several decades 8, 9, 10, 11, 12, 13, 14, 15, 16, 17. One of the main goals of modern academic and industrial research is device miniaturization, and a bottom–up or molecular approach to building components represents an attractive methodology 6, 7. Magnets are ubiquitous in modern society, employed in an enormous range of applications from information storage, biomedical imaging and cancer therapy to space research 1, 2, 3, 4, 5. As these are determined by intermolecular distance, ‘squeezing’ the molecules closer together generates remarkable enhancements in ordering temperatures, with a linear dependence of T c with pressure.
Here we report the effect of pressure on two such mononuclear rhenium(IV) compounds that exhibit long-range magnetic order under ambient conditions via a spin canting mechanism, with T c controlled by the strength of the intermolecular interactions. A lesser known family of magnetically ordered complexes are the monometallic compounds of highly anisotropic d-block transition metals the ‘transformation’ from isolated zero-dimensional molecule to ordered, spin-canted, three-dimensional lattice being the result of through-space interactions arising from the combination of large magnetic anisotropy and spin-delocalization from metal to ligand which induces important intermolecular contacts.
Materials that demonstrate long-range magnetic order are synonymous with information storage and the electronics industry, with the phenomenon commonly associated with metals, metal alloys or metal oxides and sulfides.