  The discoveries of two-dimensional ferromagnetism and magnetic semiconductors
highly enrich the magnetic material family for constructing spin-based
electronic devices but with an acknowledged challenge that the Curie
temperature (Tc) is usually far below room temperature. Many efforts such as
voltage control and magnetic ion doping are currently underway to enhance the
functional temperature, in which the involvement of additional electrodes or
extra magnetic ions limits their plenty of applications in practical devices.
Here we demonstrate that the magnetic proximity, a robust effect but with
elusive mechanisms, can induce room-temperature ferromagnetism at the interface
between sputtered Pt and semiconducting Fe3GeTe2, both of which do not show
ferromagnetism at 300 K. The independent electrical and magnetization
measurements, structure analysis, and control samples with Ta highlighting the
role of Pt confirm that the ferromagnetism with the Tc of above 400 K arises
from the Fe3GeTe2/Pt interfaces, rather than Fe aggregation or other artificial
effects. Moreover, contrary to conventional ferromagnet/Pt structures, the spin
current generated by the Pt layer is enhanced more than two times at the
Fe3GeTe2/Pt interfaces, indicating the potential applications of the unique
proximity effect in building high-efficient spintronic devices. These results
may pave a new avenue to create room-temperature functional spin devices based
on low-Tc materials and provide clear evidences of magnetic proximity effects
by using non-ferromagnetic materials.
