Magnetic-Field-Induced magnetic phase transitions associated with ferroelectricity in multiferroic ErMn ₂O ₅

Microscopic magnetic properties under the application of a magnetic field were investigated in multiferroic ErMn2O5 using neutron diffraction. Below T = 8K upon applying a magnetic field along the c-axis, an incommensurate- commensurate-incommensurate magnetic phase transition occurred. On the contrary, when the magnetic field was applied parallel to the a-axis, no phase transition occurred up to H = 5 T. H-T phase diagrams obtained in the present study show a one-to-one correspondence with H-T phase diagrams for previously obtained dielectric properties, indicating that the field-induced dielectric transition was triggered by magnetic phase transition. The contrastive phase diagram between H || c and H || a suggests that the induced Er ³⁺ magnetic moment contributed significantly to the magnetic and dielectric responses to the magnetic field.