Most magnetic molecule

The most magnetic molecule is (CpiPr5)2Tb2I3, which has a coercive magnetic field of more than 25 tesla at -223 C (-369 F). The molecule was engineered by an international team whose results were published in Science on 13 Jan 2022.

The key innovation that made this record-breaking molecule possible is a technique called lanthinide-lanthinide bonding. This uses a bridging molecule composed of iodine and carbon atoms to hold two ions of a lanthinide-series metal (such as Terbium, Dyprosium or Gadolinium) together.

To build these magnets, the compound had to be cooled to between 50 and 60 Kelvin (-223 to -213 Celsius). The resulting magnetic field is stronger than any commercially available permanent magnet.

The magnet was tested by applying an external magnetic field to try and flip the molecule’s magnetic orientation. The stronger the molecule’s magnetism, the larger the field required to flip it.

The molecule containing terbium could withstand magnetic fields of 25 Tesla, which is more than 100 times stronger than the most powerful iron-based magnets and 16 times stronger than the supercooled magnets in an MRI machine.

The previous record for a single-molecule magnet was 7.9 Tesla at a temperature of 10 Kelvin. Future developments of this technology could enable a new generation of extremely high powered permanent magnets for use in generators, electric motors and scientific equipment.