Miniature capacitive Faraday force magnetometer for magnetization measurements at low temperatures and high magnetic fields

Abstract

A Faraday force magnetometer is presented for measurements of magnetization at temperatures down to 100 mK and in magnetic fields up to 14 T. The specimen is mounted on a flexible cantilever forming a force-sensing capacitor in combination with a fixed back plate. Two different cantilever designs are presented. A torsion resistant cantilever allows us to measure the magnetization of highly anisotropic single crystal samples. Measurements of the metal organic quantum magnets (C5H12N)2CuBr4 (BPCB) and NiCl2 · 4 SC(NH2)2 (DTN) demonstrate the device’s capabilities. Routinely, a specimen’s magnetic moment is measured with a resolution better than 10−7 A m2 (10−4 emu). The device is miniaturized to fit in almost any cryostat.