  Antiferromagnetic (AFM) FePS3 has gained significant interest recently for
its potential applications in spin-related devices. A single layer is comprised
of a honeycomb network, stabilized by long-range spin-exchange interactions,
with a zigzag or Neel arrangement of the Fe-atoms. This study exposed, for the
first time, a strong impact of lateral crystal distortion on the magnetic
arrangement and optical properties of FePS3. This impact was deciphered by
correlating photoluminescence (PL) observations with single-crystal XRD which
uncovered anisotropy in the a/b crystallographic plane. Thus, induceing a
breakage in the inversion symmetry in FePS3 causing changes in it's electronic
and optical transitions. The MPL observations exhibited an unexpected band-edge
circularly polarized recombination emission, while off-band-edge transitions
were linearly polarized. Also, temperature-dependent MPL measurements reflected
zigzag-AFM at low temperatures and the coexistence of zigzag or Neel at mid
temperatures. Theoretical calculation implementing anisotropy in spin-exchange
interactions among Fe atom's nearest neighbors revealed stabilized zigzag
arrangement tilted away from the a-axis. Furthermore, DFT calculations of the
electronic band-edge predicted split states in degenerate symmetric points
(K+/K-) for zigzag structure and non-degenerate for the Neel arrangement.
Highlighting the importance of the inclusion of a crystallographic anisotropy
parameter for the simulation of the experimental observations.
