Tiny adiabatic-demagnetization refrigerator for a commercial superconducting quantum interference device magnetometer

Abstract

A tiny adiabatic-demagnetization refrigerator (T-ADR) has been developed for a commercial superconducting quantum interference device magnetometer [Magnetic Property Measurement System (MPMS) from Quantum Design]. The whole T-ADR system is fit in a cylindrical space of the diameter $8.5$ mm and the length $250$ mm, and can be inserted into the narrow sample tube of MPMS. A sorption pump is self-contained in T-ADR, and hence no complex gas handling system is necessary. With the single crystalline Gd${}_3$Ga${}_5$O${}_{12}$ garnet ($\sim 2$ grams) used as a magnetic refrigerant, the routinely achievable lowest temperature is $\sim 0.56$ K. The lower detection limit for a magnetization anomaly is $\sim 1\times 10^{-7}$ emu, estimated from fluctuation of the measured magnetization. The background level is $\sim 5\times 10^{-5}$ emu below 2 K at $H=100$ Oe, which is largely attributable to a contaminating paramagnetic signal from the magnetic refrigerant.

8 pages, 8 figures, accepted for publication in Rev. Sci. Inst

References in corpus (2)

• Enhanced magnetocaloric effect in frustrated magnets
• Reducing the magnetic susceptibility of parts in a magnetic gradiometer