Abstract Precise magnetic field sensing is important for both weak-field metrology and searches for exotic interactions. Levitated ferromagnetic systems are promising for this purpose because mechanical isolation suppresses contact-induced noise. For short-range searches, however, it remains important to establish whether such platforms can provide useful magnetic sensitivity while retaining a compact sensing volume. Here we show that a levitated ferromagnetic torsion oscillator operates as a compact room-temperature magnetometer with a sensor volume of (2.5 mm) 3 and a magnetic sensitivity of 391 ± 59 fT ⋅ Hz −1/2 at 4.99 Hz. We further show that its compact sensing volume and magnetic sensitivity make it suitable for probing short-range spin-dependent interactions through pseudomagnetic-field detection. This work establishes a compact approach to precision magnetometry and provides a basis for future searches for exotic interactions.
Ren et al. (2026) studied this question.