  Spin-dependent fifth-forces are associated with particles beyond the standard
model. In particular, light pseudo-scalar bosons mediate long-range forces,
allowing mass to interact with spins. The search of these interactions can be
performed by periodically varying the distance between a source mass and a spin
ensemble, in order to modulate the force intensity and detect it with precision
magnetometry techniques. In our setup the force arises from room temperature
lead masses and is detected in a paramagnetic crystal at 4.2\,K, whose
magnetisation is monitored by a SQUID-based magnetometer with the sensitivity
of $53\,\mathrm{aT/\sqrt{Hz}}$. Our measurement places the most stringent
constraints on a spin-mass interaction in the ranges 1\,cm to 10\,m and 10\,km
to 300\,km, improving existing limits up to more than two orders of magnitude.
We show that this experimental technique may be further leveraged to explore a
vast region of the fifth force's parameter space, with an interaction range
longer than a few centimetres.
