  In this paper, we present a coupled experimental/theoretical investigation of
pressure effect on the ferromagnetism of LaCrGe3 and LaCrSb3 compounds. The
magnetic, electronic, elastic and mechanical properties of LaCrGe3 and LaCrSb3
at ambient condition are studied by first-principles density functional theory
calculations. The pressure dependences of the magnetic properties of LaCrGe3
and LaCrSb3 are also investigated. The ferromagnetism in LaCrGe3 is rather
fragile with a ferro- to paramagnetic transition at a relatively small pressure
(around 7 GPa from our calculations, and 2 GPa in experiments). The key
parameter controlling the magnetic properties of LaCrGe3 is found to be the
proximity of the Cr DOS to the Fermi surface, a proximity that is strongly
correlated to the distance between Cr atoms along the c-axis, suggesting that
there would be a simple way to suppress magnetism in systems with one
dimensional arrangement of magnetic atoms. By contrast, the ferromagnetism in
LaCrSb3 is not fragile. Our calculation results are consistent with our
experimental results and demonstrate the feasibility of using first-principles
calculations to aid experimental explorations in screening for materials with
fragile magnetism.
