Frustrated systems with low-dimensional magnetism for magnetic refrigeration and hydrogen liquefaction

Carbon-free hydrogen represents one of the pillars of global energy transformation.

However, higher efficiency within the hydrogen supply chain, including liquefaction, is the crucial prerequisite to reduce its cost and trigger its wider use.

Magnetic refrigeration, which utilizes the magnetocaloric effect, promises to double the efficiency of hydrogen liquefaction compared to gas-compression cryocooling, but the technologies available at present mostly employ magnetocaloric materials containing strategically important rare-earth (RE) metals and expensive superconducting magnets.

We propose to search for suitable RE-free materials within an emerging class of magnetocalorics based on frustrated magnets, which are especially suitable for cooling at cryogenic temperatures.

According to theoretical predictions and pioneering studies, these materials offer high effectivity in permanent magnets, higher cooling rates, and a larger temperature span than non-frustrated systems. The RE-free frustrated magnetocalorics have been little prospected so far to achieve the limits of their efficiency.

The project aims to (1) synthesize novel RE-free frustrated magnets with low-dimensional magnetic motifs and to enhance their magnetocaloric performance at cryogenic temperatures by suitable chemical modification, while (2) exploring correlations between the magnetocaloric effect, local atomic and magnetic structure, and magnetic fluctuations.

The synthesis of novel compounds will be followed by magnetometry and calorimetry, while local information will be extracted from Mssbauer spectroscopy and neutron methods. Theoretical calculations will complement the experiment.

The fellow and the host will combine their fields of expertise, the low-temperature physics and solid-state chemistry, to elucidate the phenomena behind the magnetocaloric effect in frustrated systems and ultimately to design efficient magnetocalorics that beat the present obstacles.