The energy consumed for cooling (refrigeration, freezing, air-conditioning) is rapidly increasing and predicted to overtake the energy share needed for heating within the next 35 years. Magnetic refrigeration is viewed as an environmentally friendly and efficient alternative for vapor cooling technologies and can even be used in extreme low temperature applications as e.g. for hydrogen liquefaction. However, after several decades of research the pool of materials suitable for magnetic refrigeration is still an easy-to-grasp number. Thus, the challenge is to identify non-hazardous, low-cost, abundant materials being suitable for such refrigeration devices. In this work we tackle this challenge by combining a high-throughput search with  first principles methods  which allows to accurately predict the magnetocaloric properties of the candidate systems – fast and resource saving compared to experiment.
Materials with potential magneto-structural phase transition (MST) such as Heusler alloys [1] or MnNiSi which undergoes a phase transition from an orthorhombic low-temperature phase to a hexagonal high-temperature (paramagnetic) phase particularly interesting if the temperature-gap between the two phase transitions can be closed. For MnNiSi this can be achieved by Fe and Al doping and for Mn_1-xFe_xNiSi_0.95Al_0.5 we observe a giant magnetocaloric effect at room temperature. [2]
Inspired by these observations we designed a high-throughput search method to identify more candidate phases with MST. We combined big data searches with ab initio methods and spin dynamics simulations. The approach was in a first step verified and optimized using well-known magnetocaloric materials. [3,4]  Some 20 systems with several polymorphs passed the search filters including some known systems such as Heusler compounds, which underpins the validity of our search algorithm. Several candidates show potential for an MST near room temperature. Their magnetic properties have been studied in our theoretical approach and will be discussed as well as the expected magnetocaloric performance.

[1] V. D. Buchelnikov et al., Physical Review B 81, 094411 (2010)
[2] S. Ghorai, under review (https://doi.org/10.48550/arXiv.2307.00128)
[3] R. Martinho Vieira et al., Journal of Alloys and Compounds 857, 157811(2021)
[4] R. Martinho Vieira et al., Materials Research Letters 3, 156 (2022)