A team led by researchers from ICMAB-CSIC and the University of Barcelona (UB) has designed a new molecular compound based on gadolinium, which opens new frontiers in magnetic refrigeration. It is of particular interest in the field of molecular magnetism and the design of devices with technological applications at the nanoscale.
Future devices, such as those being developed for quantum computing and high-density information storage, need to operate at cryogenic temperatures, below 100 degrees Celsius. Gadolinium (Gd), pictured here, is a rare earth chemical element that can act as a magnetic refrigerant at extremely low temperatures. Image: Wkimedia
The electronic devices we will use in the future will become smaller and more powerful. In addition, some devices, such as those being developed for quantum computing and high-density information storage, need to operate at cryogenic temperatures. Cooling systems will therefore be needed to keep the chips at very low temperatures, and these cooling systems will have to operate effectively at the tiny scales required by the new devices
One of the options currently being explored are materials with a magneto-heat effect, which are capable of cooling when exposed to magnetic fields. One material known to have such an effect is gadolinium (Gd), a rare earth chemical element, which can work as a magnetic refrigerant at extremely low temperatures.
On the other hand, Metal-Organic Frameworks (MOFs) are molecular materials, in which their components (metal ions) are intertwined with organic ligands to form a kind of framework, in two or three dimensions. Lanthanide-based MOFs stand out for their versatility in preparing materials with magnetic, electrical and optical properties for a wide variety of applications.
"The research of this type of multifunctional metal-organic compounds involves a multidisciplinary approach, where the characterisation of the materials through a series of techniques, including magnetometry, calorimetry, luminescence and X-ray magnetic circular dichroism, is crucial," says Elena Bartolomé, a scientist in the Department of Inorganic Molecular Materials and Smart Hybrids at the l'Institut de Ciència de Materials de Barcelona del CSIC (ICMAB-CSIC).
A team led by researchers from ICMAB-CSIC and the University of Barcelona (UB) has prepared and fully characterised a new two-dimensional MOF based on gadolinium (Gd).
In this compound, each gadolinium ion behaves as if it were a magnetised molecule. As a two-dimensional lattice composite, each monolayer forms an ordered array of single molecular magnets (SMM).
These SMMs are promising materials for information storage, with each Gd(III) ion acting as a bit. In addition, due to the presence of this element, the compound has a high magnetocaloric effect, which is equivalent to a high cooling capacity.
"This MOF is special because it is two-dimensional. Two-dimensional MOFs are the metal-organic equivalent of graphene and, similarly, they can be exfoliated in monolayers or aggregates of a few monolayers at the nanometric scale," explains Carolina Sañudo, professor in the UB's Department of Inorganic and Organic Chemistry.
The international team that has developed this work is formed by Dr. Elena Bartolomé (ICMAB-CSIC), Dr. Carolina Sañudo (UB), Guillem Gabarro Riera i Subodh Kumar (both from the UB), Jesus Jover (Institute of Theoretical and Computational Chemistry of the UB), Dr. Juan Rubio-Zuazo (European Synchrotron Radiation Facility i de l’Instituto de Ciencia de Materiales de Madrid ), Prof. Stephen Hill (National High Magnetic Field Laboratory, Tallahassee, USA) and Prof. Lapo Bogani (University of Oxford).
In their research, the team has successfully grow nanocrystals of the compound on a semiconducting silicon surface, a decisive step towards the use of molecular materials in devices for technological applications. In the field of magnetic cooling, nanocrystals deposited on the semiconductor can be used as surface coolants at very low temperatures, a property of interest for reducing the temperature inside electronic circuits or devices.
The findings of the new study indicate that it is possible to use gadolinium compounds for magnetic cooling in devices, not only because the nanostructured material can be deposited on a semiconductor, but also because the magnetocaloric effect is maintained at the nanoscale and the new compound can function as a magnetic coolant on the surface.
Reference article:
Kumar, S., Gabarró-Riera, G., Arauzo, A. Hrubý, J., Hill, S., Bogani, L., Rubio-Zuazo, J., Jover, J., Bartolomé, E., Sañudo, C. (2024) «On-surface magnetocaloric effect for a van derWaals Gd(III) 2D MOF grown on Si». Journal of Materials Chemistry A. 12(11), 6269-6279. https://pubs.rsc.org/en/content/articlelanding/2024/ta/d3ta06648g