Magnetoelectric effect of Mn3B7O13I boracite

Magnetization measurements with a SQUID magnetometer have been carried out on a ferroelectric single domain sample along the three orthorhombic directions. The Neel (Curie) temperature was found at 26+/-0.5 K and the spontaneous magnetization of the weakly ferromagnetic phase to lie along the orthorhombic b direction which is compatible with the magnetic space group Pc'a2(1)' (point group m'm2') found by neutron diffraction. Magnetoelectric measurements carried out on an electrically poled single domain platelet are in agreement with the magnetic point group m'm2'. Using a quasi-static method, the magnetoelectric coefficients alpha(32) (linear effect) and beta(311), beta(322) and beta(333) (quadratic effect) have been measured at 4.2 K. The Curie temperature has been determined by a dynamic magnetoelectric measurement and found to be 25.5+/-0.5 K. The magnetoelectric coefficients being rather weak implies the use of large single domain samples and of a highly sensitive experimental setup.