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Numerical modelling and experimental validation of adiabatic demagnetization refrigeration at sub-Kelvin temperatures.

Number: 0012

Author(s) : CHANDAVAR R. A., SCHÜßLER P., KINAST A., WENDL A., ROTHE J., EIBENSTEINER K., SPALLEK J., SÄUBERT S.

Summary

Adiabatic demagnetization refrigeration (ADR) offers helium-3-free access to millikelvin temperatures and is therefore ideally suited as cooling platform for scaled-up quantum technology applications. Designing and optimizing ADR stages for the sub-100 mK regime requires quantitative models capable of predicting system performance under realistic operating conditions. At these temperatures, thermal boundary resistance, strongly nonlinear magnetocaloric behaviour, eddy current heating, and parasitic heat loads become dominant effects that simple analytical estimates cannot capture. This paper presents a coupled numerical model for the thermal dynamics of the refrigerant, i.e. a paramagnetic salt, and the thermal interface structure, i.e. a copper matrix, in a single ADR stage and validates it against experimental measurements. The two key material inputs, the field-dependent specific heat of the salt and the temperature dependent thermal conductance of the salt-copper interface, are independently characterized for Ferric Ammonium Alum (FAA) and Chromic Potassium Alum (CPA). Interface conductance measurements confirm a T3 dependence for both materials, consistent with acoustic mismatch theory. Specific heat measurements validate the magnetocaloric model with literature parameters across the full field range investigated. The model accurately reproduces temperature evolution during magnetic field ramps as well as magnetic field decay while stabilizing a temperature for both materials.
 

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Pages: 10 p.

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Details

  • Original title: Numerical modelling and experimental validation of adiabatic demagnetization refrigeration at sub-Kelvin temperatures.
  • Record ID : 30035057
  • Languages: English
  • Subject: Technology
  • Source: 11th IIR Conference on Solid-State Cooling, Heating and Energy Harvesting.
  • Publication date: 2026/06/07
  • DOI: http://dx.doi.org/10.18462/iir.thermag.2026.0012

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