Gigantic magnetoelectric effect caused by magnetic-field-induced canted antiferromagnetic-paramagnetic transition in quasi-two-dimensional Ca2CoSi2O7 crystal

We have investigated the magnetic and dielectric properties of Ca2CoSi2O7 crystal. The dielectricity and magnetism of Ca2CoSi2O7 are strongly coupled below a canted antiferromagnetic transition temperature (T-N). Magnetic fields induce electric polarization below T-N. Interestingly, the magnetic-field-induced electric polarization is detected even without poling electric fields. Below T-N, a canted antiferromagnetic-paramagnetic transition is induced by magnetic fields. The large magnetocapacitance is observed around T-N. The origin of the large magnetocapacitance is due to the magnetic-field-induced the canted antiferromagnetic-paramagnetic transition.