Magnetic and dielectric properties of A2CoSi2O7 (A=Ca, Sr, Ba) crystals

M. Akaki; J. Tozawa; D. Akahoshi; H. Kuwahara

doi:10.1088/1742-6596/150/4/042001

paper

Magnetic and dielectric properties of A2CoSi2O7 (A=Ca, Sr, Ba) crystals

arXiv:0901.1749 · doi:10.1088/1742-6596/150/4/042001

Abstract

We have investigated the magnetic and dielectric properties of $A_{2}$ CoSi $_{2}$ O $_{7}$ ( $A$ =Ca, Sr, and Ba) crystals with a two-dimensional network of CoO $_{4}$ and SiO $_{4}$ tetrahedra connected with each other through the corners. In Ca $_{2}$ CoSi $_{2}$ O $_{7}$ , a weak ferromagnetic transition occurs at 5.7 K, where the dielectric constant parallel to the c axis shows a concomitant anomaly. The large magnetocapacitance effect is observed below 5.7 K; $Δ ε (H) / ε (0) \equiv [ε (H) - ε (0)] / ε (0)$ reaches 13 % at 5.1 K\@. These results indicate a strong coupling between the magnetism and dielectricity in Ca $_{2}$ CoSi $_{2}$ O $_{7}$ . Sr $_{2}$ CoSi $_{2}$ O $_{7}$ shows a similar magnetoelectric behavior to that of Ca $_{2}$ CoSi $_{2}$ O $_{7}$ . In contrast, in Ba $_{2}$ CoSi $_{2}$ O $_{7}$ , which has the different arrangement of SiO $_{4}$ and CoO $_{4}$ tetrahedra from that of Ca $_{2}$ CoSi $_{2}$ O $_{7}$ , the magnetocapacitance is hardly observed. The key for the magnetocapacitance effect of $A_{2}$ CoSi $_{2}$ O $_{7}$ lies in the quasi-two-dimensional crystal structure.

arXiv comment4 pages, 2 figures, proceeding of 25th International Conference on Low Temperature Physics LT25

Magnetic and dielectric properties of A2CoSi2O7 (A=Ca, Sr, Ba) crystals

Abstract

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