Super refrigerator offers an alternative to helium for cooling for quantum and space applications

13 Feb 2026

Early career researcher Mingfang Shu and her collaborators have achieved a spin-based supersolid state in an intermetallic alloy for the first time: a new breakthrough in helium-3-free solid-state refrigeration. Extremely low temperatures (sub-Kelvin) are essential for cutting-edge studies in quantum computing, precision measurement, and large scientific facilities.

In ECA, the local moments form a spin-supersolid state and serve as an entropy reservoir for magnetic cooling, whereas conduction electrons with a large Fermi surface offer an expressway for heat conduction. The entropy contributions follow distinct power laws: Se ~ T for electrons and Sph ~ T3 for phonons. At the supersolid QCP, the magnetic entropy scales as Sm ~ T, dominating the total entropy at low temperatures. The metallic thermal conductivity (~T), which decreases much slower than that in insulating systems (~T3).

Local moments in ECA form a spin-supersolid state and serve as an entropy reservoir for magnetic cooling, whereas conduction electrons with a large Fermi surface offer an expressway for heat conduction.

Currently, mainstream global dilution refrigeration technologies rely heavily on 3He, a rare isotope of helium. However, 3He is a globally scarce resource, and many countries currently rely entirely on imports, making it a key constraint on the development of innovative research fields and quantum devices.

³He-free solid-state refrigeration technologies, which operate through adiabatic demagnetisation, have long been hampered by the problem that their core materials have poor thermal conductivity. This hinders the quick dissipation of heat in these materials, in an analogous way that wood rather than metal is being used in alpine chalets to thermally insulate the inside from the outside. Ultimately this poor thermal conductivity results in insufficient refrigeration power.

Being able to combine a large cooling capacity with high thermal conductivity is the core challenge that needs to be overcome. In this paper, published in Nature, a joint research team has achieved a significant breakthrough in addressing this problem. The study’s co-first author was Mingfang Shu, a postdoctoral researcher in Professor Jie Ma’s group at Shanghai Jiao Tong University (now an early-career researcher at China’s Jiliang University), who worked with research groups across China, Pascal Manuel and Dmitry Khalyavin at ISIS, and the muon division from KEK.

By closely integrating high-quality single-crystal growth, ultra-low temperature thermodynamic measurements, neutron diffraction experiments on the WISH beamline at ISIS, and quantum many-body theory calculations, the research team has, for the first time, revealed the existence of a ‘metallic spin supersolid’. The team characterised the material, which is an alloy with a frustrated triangular lattice, and elucidated its magnetic ground state and underlying microscopic interactions.

In this material, EuCo₂Al₉(ECA), a giant magnetocaloric effect and ultra-high thermal conductivity coexist at extremely low temperatures. These seemingly contradictory properties allow it to not only overcome a long-standing performance bottleneck in solid-state refrigeration but also provide a novel refrigeration solution that does not rely on the scarce resource ³He. It therefore potentially offers a self-controllable ‘super refrigerator’ for cutting-edge fields such as quantum computing.

To understand the material’s unique properties, the team came to ISIS to carry out neutron diffraction experiments on the WISH beamline. Using the high sensitivity of the instrument and ultra-low temperature experimental conditions, they systematically studied the evolution of the magnetic structure as a function of temperature and applied magnetic field.

Unlike for other candidate spin supersolid systems, the magnetic structure of ECA is clearly unambiguous, leaving no doubts in the experimental realisation of this exotic quantum phenomenon

Pascal Manuel

This enabled the authors to successfully identify the key ingredients of the spin supersolid state. The idea of supersolid was originally formulated many years ago for an exotic quantum state of matter that simultaneously behaves as a rigid crystal and superfluid. Later the idea was adopted for magnetic phenomena, and it was referred to as spin supersolid.

The magnetic ground state observed in this study implies the existence of a ‘solid’ spin component, similar to how atoms are arranged in a crystal, where changing the spins costs energy, and a soft ‘superfluid’ component, which can be continuously rotated in a crystal without an energy penalty.

This remarkable ground state plays an important role in the excellent refrigerating properties of EuCo₂Al₉. The neutron diffraction results showed a high degree of agreement with theoretical calculations, providing crucial experimental evidence for the theoretical concept.

“Unlike for other candidate spin supersolid systems, the magnetic structure of EuCo₂Al₉ is clearly unambiguous, leaving no doubts in the experimental realisation of this exotic quantum phenomenon” explains ISIS’ Pascal Manuel.

This research marks a new stage towards possible quantum devices harnessing the exotic spin supersolid property, moving beyond fundamental research and opening up new systems and directions for metallic cooling materials. The researchers hope to create a ‘super refrigerator’ for the quantum technology era, providing a highly promising solution to address the challenges of insufficient solid-state cooling power and reliance on ³He in quantum technology, space science and other fields.

The full paper can be found on the Nature website.