  Van der Waals material Fe$_5$GeTe$_2$, with its long-range ferromagnetic
ordering near room temperature, has significant potential to become an enabling
platform for implementing novel spintronic and quantum devices. To pave the way
for applications, it is crucial to determine the magnetic properties when the
thickness of Fe5GeTe2 reaches the few-layers regime. However, this is highly
challenging due to the need for a characterization technique that is local,
highly sensitive, artifact-free, and operational with minimal fabrication.
Prior studies have indicated that Curie temperature TC can reach up to close to
room temperature for exfoliated Fe$_5$GeTe$_2$ flakes, as measured via
electrical transport; there is a need to validate these results with a
measurement that reveals magnetism more directly. In this work, we investigate
the magnetic properties of exfoliated thin flakes of van der Waals magnet
Fe$_5$GeTe$_2$ via a quantum magnetic imaging technique based on nitrogen
vacancy diamond. Through imaging the stray fields, we confirm room-temperature
magnetic order in Fe$_5$GeTe$_2$ thin flakes with thickness down to 7 units
cell. The stray field patterns and their response to magnetizing fields with
different polarities point to a perpendicular easy-axis anisotropy.
Furthermore, we perform imaging at different temperatures and determine the
Curie temperature of the flakes at Tc~300 K. These results provide the basis
for realizing a room-temperature monolayer ferromagnet with Fe$_5$GeTe$_2$.
This work also demonstrates that the imaging technique enables a rapid
screening of multiple flakes simultaneously, thereby paving the way towards
high throughput characterization of potential 2D magnets near room temperature.
