  wo-dimensional (2D) materials unique properties and their promising
applications in post-silicon microelectronics have attracted significant
attention in the past decade. Recently, ferromagnetic order with out-of-plane
easy axis in a monolayer of CrI3 has been observed and reported, with a Curie
temperature of 45 K. Here we study, using density functional theory (DFT)
calculations, how hydrogen and oxygen adsorption affects the structural,
electronic, and magnetic properties of a CrI3 monolayer. Our results show that
while the structure remains almost unchanged by the adsorption of hydrogen,
adsorption of oxygen completely distorts it. We have also found that both the
adsorption of hydrogen and oxygen atoms significantly influences the electronic
and magnetic properties of the monolayer. While hydrogen quenches the magnetic
moments of Cr atoms, oxygen introduces an impurity band in the gap.
Interestingly, we find a strong enhancement of the Curie temperature by full
hydrogenation, while the results are not conclusive for O. This result suggests
a simple and effective approach to manipulate the electronic and magnetic
properties of 2D magnets for spintronics applications.
