Structural investigation of magnetocapacitive SmMnO₃

Structural deformation of a magnetocapacitive material SmMnO₃ was studied by X-ray diffraction measurement in a magnetic field. This antiferromagnetic material shows a jump in dielectric constant at 9 K only when a magnetic field of a few tesla is applied. In-field X-ray diffraction measurements clarified that there is no sudden change in structure that involves atomic displacement within the c-plane in Pbnm notation, while the antiferromagnetic phase transition at 60 K gives rise to a noticeable rotation of the MnO₆ octahedra. This rotation occurs to maximize the energy gain through the exchange interaction.