A Polar Corundum Oxide Displaying Weak Ferromagnetism at Room Temperature

Combining long-range magnetic order with polarity in
the same structure
is a prerequisite for the design of (magnetoelectric) multiferroic
materials. There are now several demonstrated strategies to achieve
this goal, but retaining magnetic order above room temperature remains
a difficult target. Iron oxides in the +3 oxidation state have high
magnetic ordering temperatures due to the size of the coupled moments.
Here we prepare and characterize ScFeO3 (SFO), which under
pressure and in strain-stabilized thin films adopts a polar variant
of the corundum structure, one of the archetypal binary oxide structures.
Polar corundum ScFeO3 has a weak ferromagnetic ground state
below 356 Kthis is in contrast to the purely antiferromagnetic
ground state adopted by the well-studied ferroelectric BiFeO3.