Magnetic Proximity Coupling to Defects in a Two-Dimensional Semiconductor

The ultrathin structure and efficient spin dynamics of
two-dimensional
(2D) antiferromagnetic (AFM) materials hold promising opportunities
for ultrafast memory devices, artificial intelligence circuits, and
advanced computing technology. For example, chromium thiophosphate
(CrPS4) is one of the most promising 2D A-type AFM materials
due to its robust stability in diverse environmental conditions and
net out-of-plane magnetic moment in each layer, attributed to anisotropy
in crystal axes (a and b). However,
their net-zero magnetic moment poses a challenge for detecting the
Néel state that is used to encode information. In this study,
we demonstrate the detection of the Néel vector by detecting
the magnetic order of the surface layer by employing localized defects
in tungsten diselenide (WSe2). These defects are ideal
candidates for optically active transducers to probe the magnetic
order due to their narrow line width and high susceptibility to magnetic
field (B-fields). We observed spin-polarized charge
transfer in the heterostructure of bulk CrPS4 and single-layer
WSe2, indicating type-II band alignment as supported by
density functional theory (DFT) calculations. In the A-type AFM regime,
the intensity of both right-handed and left-handed circularly polarized
light emanating from the sample remains constant as a function of
the applied B-field, indicating a constant polarized
transition behavior. Our results demonstrate an approach to optically
characterizing the magnetic states of 2D bulk AFM material by using
both localized and delocalized defect excitons as a probe, highlighting
avenues for future research and technological applications.