Ultra-high sensitivity B-H looper/AC susceptometer

An ultra-high-sensitivity, versatile B-H looper/AC susceptometer is described. The design is based on the well-known inductance technique, and uses modern low-noise components to achieve the high sensitivity. The mechanical assembly is designed for use inside a glass dewar, enabling measurements to be made at any temperature between 4.2 K and 300 K. B-H loops at 5 kHz with up to 3.09 kOe applied field can be measured much faster and with greater sensitivity than with a SQUID (superconducting quantum interference device) magnetometer. Initial AC susceptibility can be measured over a frequency range of 12 Hz to 120 kHz.<
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