Magnetic structures of metastable perovskites ${\mathrm{ScCrO}}_3, {\mathrm{InCrO}}_3$, and ${\mathrm{TlCrO}}_3$, stabilized under high-pressure and high-temperature conditions, have been studied by neutron powder diffraction. Similar to the other orthochromites ${\mathrm{LnCrO}}_3$ (Ln = lanthanide or Y), these materials crystallize into the orthorhombic structure with $Pnma{1}^{\prime }$ symmetry. The spin configuration of the metastable perovskites has been found to be $C$ type, contrasting with the $G$-type structure usually observed in ${\mathrm{LnCrO}}_3$. First-principles calculations demonstrate that the $C$-type structure found in ${\mathrm{ScCrO}}_3$ and ${\mathrm{InCrO}}_3$ is attributed to a ferromagnetic (FM) nearest-neighbor interaction, while in ${\mathrm{TlCrO}}_3$, this type of magnetic ordering is stabilized by a strong next-nearest-neighbor antiferromagnetic (AFM) exchange. The spins in the $C$-type magnetic structure line up along the orthorhombic $b$ axis, yielding the $Pnma$ magnetic symmetry. The dominant mechanism controlling this spin direction has been concluded to be the single ion anisotropy imposed by a uniaxial distortion of ${\mathrm{CrO}}_6$ octahedra.

• Received 9 November 2016
• Revised 8 February 2017

DOI:https://doi.org/10.1103/PhysRevB.95.054432