Unlocking Ultra-Cold Cooling: A Unique Magnetic Material for Next-Generation Refrigeration

Published April 14, 2025

Illustration of the triangular Eu0.9Ba0.1I2(pyrazine)3 network and the magnetic fields (blue lines) produced by the EuII ions (green spheres) that are essential to the refrigeration process.

A two-dimensional triangular network of europium ions connected by organic pyrazine molecules is shown to possess the perfect ingredients for efficient magnetic refrigeration at very low (sub-kelvin) temperatures. In particular, the large magnetic moment and high europium concentration open up exciting possibilities for efficient on-chip cooling, especially in scenarios where established inorganic refrigerants cannot be utilized.

What is the finding

Scientists discovered that a special arrangement of europium ions connected by organic molecules could be ideal for efficient magnetic cooling at extremely low temperatures. The triangular pattern prevents the europium ions from settling into an ordered magnetic state, keeping them disordered even at near absolute zero. This unique property makes the material promising for advanced cooling technologies.

Why is this important?

Scientists found that by briefly applying and then removing a magnetic field, a special material with europium ions can cool itself down. This could lead to efficient mini refrigerators for ultra-low temperatures, reducing the need for rare and costly helium-3, which is currently used for cooling below 1K.

Who did the research?

A.S. Manvell,¹ M.A. Dunstan,¹ D. Gracia,² J. Hrubý,³ M. Kubus,¹ J.N. McPherson,¹ E. Palacios,² H. Weihe,⁴ S. Hill,³ J. Schnack,⁵ M. Evangelisti,² K.S. Pedersen¹

¹TU Denmark, Denmark; ²CSIC & Universidad de Zaragoza, Spain; ³National MagLab, FSU; ⁴University of Copenhagen, Denmark; ⁵Universität Bielefeld, Germany

Why did they need the MagLab?

Scientists studied how europium ions interact in this special material, which is key to understanding its cooling ability. Electron paramagnetic resonance measurements at magnetic fields far greater than those of commercial instruments were essential for measuring these interactions and discovering how europium’s magnetic poles align. This knowledge helps explain how the material achieves ultra-low-temperature cooling.

Details for scientists

View or download the expert-level Science Highlight, A Triangular Frustrated EuII Magnetic Framework for Sub-Kelvin Refrigeration
Read the full-length publication, A Triangular Frustrated Eu(II)–Organic Framework for Sub-Kelvin Magnetic Refrigeration, in Journal of the American Chemical Society, Data Set

Funding

This research was funded by the following grants: K. M. Amm (NSF DMR-2128556); K. S. Pedersen (Villum Fonden, Sapere Aude, Carlsberg Foundation); M. Evangelisti (European Union, Gobierno de Aragón)

For more information, contact Stephen Hill.