Verification of the de Wolff hypothesis concerning the symmetry of β‐MnO 2

The symmetry lowering from tetragonal to orthorhombic is demonstrated using high‐resolution diffraction and also justified by using the magnetic superspace groups formalism for the rutile‐type compound β‐MnO 2 . The (lower) orthorhombic symmetry is observed at temperatures both below and above the Néel temperature. The magnetic ordering of β‐MnO 2 is of spin density type and not screw‐type helical. The results support the de Wolff [ Acta Cryst. (1959), 12 , 341–345] hypothesis about the orthorhombic symmetry of β‐MnO 2 .