  The exploration of van der Waals (vdWs) magnetic materials has sparked great
interest in spintronics. However, conventional methods often face challenges in
characterizing the magnetic properties of small-sized vdWs materials,
especially for antiferromagnets with extremely small magnetic moments. Here, we
demonstrate the efficacy of dynamic cantilever magnetometry (DCM) in
characterizing the magnetic properties of vdWs magnets, using an
antiferromagnetic semiconductor CrPS4. We observe continuous spin axis rotation
under a magnetic field, accurately modelled by considering the existance of
marked magnetic anisotropies. Furthermore, the dominance of out-of-plane
magnetic anisotropy in spin reorientation behavior at low temperatures
transitions to the prevalence of in-plane anisotropy with increasing
temperature, leading to a sign reversal of the frequency shift in measurements.
The peculiar magnetic phase transitions make CrPS4 an intriguing platform for
studying two-dimensional magnetism. Our findings underscore the effectiveness
of DCM in characterizing magnetic anisotropies and phase transitions in vdWs
magnets.
