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TT: Fachverband Tiefe Temperaturen
TT 60: Cryogenic Detectors and Sensors, Refrigeration and Thermometry
TT 60.7: Talk
Wednesday, March 20, 2024, 17:30–17:45, H 3025
Development of a miniaturized, modular, nuclear demagnetization stage — •Leo Maximov1, Nico Huber1, Andreas Bauer1, Yusuke Nago2, Keiya Shirahama2, and Christian Pfleiderer1 — 1Physik-Department, Technical University of Munich, D-85748 Garching, Germany — 2Keiyo University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama, Japan
Experimental studies of condensed matter systems at sub-milli Kelvin temperatures are effectively only possible by virtue of nuclear adiabatic demagnetization refrigeration (NADR). While copper is the most commonly used refrigerant for NADR, both the development and operation of copper based NADR-stages are technically demanding and limited due to the very low starting temperatures needed for demagnetization. To overcome these limitations, hyperfine-enhanced refrigerants may be used. Here, we present the design and implementation of a compact, miniaturized, modular nuclear demagnetization stage for optional use with a conventional dilution refrigerator. Comprising a superconducting aluminum heat switch, a demagnetization stage using PrNi5 with a bespoke superconducting coil, and a CMN thermometer, the setup is conceived for exploratory studies in the milli-Kelvin regime and below. Moreover, we report the successful crystal growth of polycrystalline PrNi5 as well as a comprehensive study of its low-temperature properties, particularly with regard to the potential use as a cooling medium.
Keywords: Ultra low temperatures; Nuclear adiabatic demagnetization; PrNi5; Superconducting heat switch