- The magnetic phase diagram of a polar ferrimagnet CaBaFe4O7 with a magnetic easy axis has been investigated by measurements of magnetization, specific heat, and magnetoelectricity. A ferrimagnetic transition takes place at TC1=275 K within the orthorhombic phase followed by a second magnetic transition at TC2=211 K. Below TC2, successive metamagnetic transitions occur for magnetic fields applied perpendicular to the easy axis, implying a sequential emergence of magnetic states which are neither collinear nor coplanar. The observation of the static magnetoelectric effect was limited to temperatures below 120 K due to the conducting nature of the crystals at higher temperatures. The magnitude of the ferroelectric polarization shows large changes between the different field-induced magnetic phases. The low-field state is characterized by a large linear magnetoelectric coefficient of αcc=39 ps/m, while a gigantic polarization change of ΔP=850 μC/m2 is observed for μoH=14 T applied alongThe magnetic phase diagram of a polar ferrimagnet CaBaFe4O7 with a magnetic easy axis has been investigated by measurements of magnetization, specific heat, and magnetoelectricity. A ferrimagnetic transition takes place at TC1=275 K within the orthorhombic phase followed by a second magnetic transition at TC2=211 K. Below TC2, successive metamagnetic transitions occur for magnetic fields applied perpendicular to the easy axis, implying a sequential emergence of magnetic states which are neither collinear nor coplanar. The observation of the static magnetoelectric effect was limited to temperatures below 120 K due to the conducting nature of the crystals at higher temperatures. The magnitude of the ferroelectric polarization shows large changes between the different field-induced magnetic phases. The low-field state is characterized by a large linear magnetoelectric coefficient of αcc=39 ps/m, while a gigantic polarization change of ΔP=850 μC/m2 is observed for μoH=14 T applied along the easy axis.…
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