Magnetic measurements by utilizing the self-oscillating LC-tank circuit

The techniques utilizing the inductor-capacitor (LC) self-oscillators are a versatile experimental tool for the investigation of magnetic properties. Consequently, numerous scientific measurements have employed this type of technique. An LC self-oscillator generically offers high sensitivity because of the intrinsic elimination of the large background due to a long coax cable. The self-oscillator has been successful with the frequency ranges from radiofrequency to microwave. However, the applications lack long-wavelength signals although this frequency range can bridge phenomena between the direct current (DC) and alternating current (AC) techniques. We propose and design a brand-new measurement technique based on the Colpitts oscillator (CO). To characterize the magnetic properties at low temperatures, a commercial superconducting quantum interface device (SQUID) magnetometer is usually used, which provides excellent accuracy. However, the SQUID magnetometer always requires applying a minimum DC external magnetic field of ~1 Oe, and the material with a high magnetic moment is the first choice for the best sensitivity. Whereas application of CO requires neither a large moment nor a DC applied field to obtain the best sensitivity. Due to the non-perturbative measurement using a long-wave AC and a negligible driving magnetic field, CO technology would allow the investigation of intrinsic magnetic properties. This technique is particularly useful for studying ferromagnetic materials that exhibit decentralized susceptibility near the Curie temperature. CO technique requires a relatively low power to operate, which makes the application of the CO technique at low temperatures possible. CO can also be used as an ultra-stable frequency source and can be used as a reference signal for heterodyne techniques.