Multiferroic properties of an åkermanite Sr2CoSi2O7single crystal in high magnetic fields

Abstract

The magnetic and dielectric properties ofåkermanite Sr 2 CoSi 2 O 7 single crystals in high magnetic fields were investigated. We have observed finite induced electric polarization along the c axis in high fields, wherein all Co spins were forcibly aligned to the magnetic field direction. Existence of the induced polarization in the spin-polarized state accompanied with the finite slope in the magnetization curve suggests the possible role of the orbital angular momenta in the excited states as its microscopic origin. The emergence of the field-induced polarization without particular magnetic order can be regarded as the magnetoelectric effects of the second order from the symmetry point of view. A low magnetic field-driven electric polarization flip induced by a rotating field, even at room temperature, has been successfully demonstrated.

Successive Magnetic Transitions of Ca2CoSi2O7in High Magnetic Fields

“…In addition, owing to the small exchange interaction in these materials, we can fully polarize the spins in moderately high magnetic field as demonstrated in our previous study on Sr 2 CoSi 2 O 7 . 13) In that study, we found the existence of finite electric polarization in the fully spin polarized state indicating that anitiferromagnetism is not necessary to induce electric polarization through the spin system. Actually, the magnetic field induced electric polarization was observed even at 300 K in this material.…”

One-way transparency of four-coloured spin-wave excitations in multiferroic materials

“…The magnetically induced ferroelectric polarization together with the differential magnetoelectric effect (indicated for Ca 2 CoSi 2 O 7 in the caption of Fig. 2b) 31,36 . Since directional dichroism is governed by the same differential magnetoelectric effect in the optical region, the sign of the integral in Equation 5 should simultaneously be reversed.…”

Evolution of two-dimensional antiferromagnetism with temperature and magnetic field in multiferroicBa2CoGe2O7

“…Emergence of ferroelectricity in several members of the melilite family, including Ba 2 CoGe 2 O 7 , below their magnetic ordering temperature has been recently discovered [1,2]. The remarkable and complex response of these materials to magnetic and electric fields can be predicted by considering the magnetic point group symmetries of both the paramagnetic and magnetically ordered phases [3,4].…”