SHRiMp

SHRIMP is a magnetometer that combines operation at room temperature, high working frequency and ease of implementation, making it useful for a variety of applications. The sensitivity limit of this instrument is equal to or better than that of the present state-of-the-art magnetometers, while the working principle is based on field modulation usually used for the measurement of electron spin resonances. To improve sensitivity, the magnetic material can be coupled to a resonator. It is a resonant instrument, which therefore operates at a certain frequency, which however can be easily changed by acting on the magnetizing field. Typical working frequencies are from ten MHz up to GHz.

Detecting very weak magnetic fields is an ongoing technological challenge, motivated by the numerous applications of the magnetometers. The most sensitive existing magnetometers are the SQUID (Superconducting Quantum Interference Device) and SERF (Spin-Exchange Relaxation Free), and are based on superconducting junctions and alkaline atoms, respectively. In the case of SHRIMP, an external field is detected by the fact that it causes a rapid change in the electronic resonance frequency induced by a static field. The addition of a resonator makes it possible to considerably reduce detection noise, but has the drawback of imposing a minimum working frequency (around tens of MHz).

The main advantages of SHRIMP are:

• • possibility of operating at room temperature, unlike SQUIDs which instead require cryogenic temperatures;
  • unlike SERFs, sensitivity is independent of the physical size;
  • the input impedance need not be 50 Ω.