Cryogenic magnetic force microscopy at 35 T and Sub-3 K in a water-cooled magnet

Probing microscopic magnetic textures under ultra-high magnetic fields is critical for uncovering emergent quantum phenomena but remains experimentally challenging. Here, we present the first cryogenic magnetic force microscope (MFM) operating at temperatures below 3 K and magnetic fields up to 35 T in a water-cooled resistive magnet. A static exchange-gas helium cryostat provides a stable, chemically inert, and low-vibration cryogenic environment, while a nonmetallic MFM head and high-Q cantilever tips effectively suppress strong-field and mechanical disturbances. The frequency-shift noise is as low as ∼60 mHz at 33 T, well below typical magnetic signal amplitudes (>200 mHz), ensuring sustained high sensitivity throughout field ramping. Using this platform, we imaged field-driven magnetic textures in a multiferroic SrRuO3 film at 2.7 K from 0 to 35 T, revealing robust magnetic-domain behavior locked by ferroelastic domains. This work establishes a powerful platform for real-space imaging of quantum magnetism under extreme conditions.