Traditionally, chemistry was divided between inorganic materials, built from atoms in extended lattices, and organic materials, built from atoms joined into discrete molecules or chains. First developed in the 1990s, metal–organic frameworks (MOFs) are a hybrid of the two: extended lattices in which organic molecules form the links between metal centres.

The great benefit of MOFs – and the reason they were the subject of last year’s Nobel Prize in Chemistry – is that they can be designed to have all sorts of properties, just by tuning the makeup of the molecular linkers.

Most MOFs have employed long molecules to make highly porous, sponge-like materials, able to store gases or act as catalysts. But some researchers have realised that it is possible to make MOFs that are tuneable versions of known crystal structures.

One of these is perovskite, a crystal built from a regular three-dimensional network of corner-sharing building blocks, with promising applications in photovoltaics, superconductivity and novel magnetism. So far, however, perovskite-inspired MOFs exhibiting strong and persistent magnetic order have been hard to realise.

Created by researchers at the Technical University of Denmark (TDU) and elsewhere, the new magnetic MOF is based on an ReO3-type structure – similar to perovskite, minus the large ion that usually sits in the cavities of the lattice. The metal centres are chromium, each carrying three units of spin, while the linkers are pyrazine radicals, each carrying one. With one chromium for every three pyrazine radicals, the two sublattices were expected to behave like opposing sides in an evenly matched tug of war. This is known as a compensated ferrimagnet – a structure with strong internal magnetic order, but with almost zero magnetism overall.

Material's magnetisation measured

The team made the crystal by heating a chromium precursor with pyrazine, and confirmed its unusual magnetism using a mix of techniques. One of these was X-ray magnetic circular dichroism (XMCD), which allows researchers to probe magnetism at specific atomic sites. According to Andrei Rogalev, the scientist in charge at ID12 where the XMCD experiment was performed, the stability of the ESRF’s X-ray beam was crucial in confirming that the chromium ions carry a magnetic moment, even though the material as a whole had almost no net magnetism – the hallmark of compensated ferrimagnetism.

Measurements of the material’s magnetisation over a range of temperatures showed that the near-cancellation of magnetism persists from low temperature to well above room temperature. “That is a key point,” says Kasper Pedersen at the DTU. “In many compensated ferrimagnets, the net magnetisation vanishes only near a particular temperature. Here, the remanent magnetisation remains tiny and essentially constant from low temperature to above 300 K, which is why we frame it as an especially robust compensated ferrimagnet.”

Materials of this kind are of interest for spintronics, where information is carried by electron spin rather than charge. Because their internal magnetism almost cancels out, they produce very little stray magnetic field, making them easier to pack together in devices without interference.

The next step will be to tune the material’s electronic state – for example by chemical substitution – to explore whether related frameworks can be pushed towards other magnetic or conducting behaviours, and to investigate whether they can be grown as thin films for integration into devices. But the material has already exceeded expectations. “In the end, it displayed a rarer combination of properties than we had hoped for,” says Pedersen.

Reference:

Aribot, F., et al. Nat. Chem. (2026). https://doi.org/10.1038/s41557-026-02131-8

Top image: Structure of the team’s metal–organic framework. Consisting of chromium metal centres with pyrazine linkers, the material has an internal magnetism that almost entirely cancels out, making it an unusually stable compensated ferrimagnet. Credit: Frédéric Aribot