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

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; $\Delta \epsilon (H)/\epsilon (0)\equiv [\epsilon (H)-\epsilon (0)]/\epsilon (0)$ 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.

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

References in corpus (2)

• Spin current and magneto-electric effect in non-collinear magnets
• Ferroelectric polarization flop in a frustrated magnet MnWO${}_4$ induced by magnetic fields

Cited by in corpus (2)

• Multiferroic properties of an åkermanite Sr${}_2$CoSi${}_2$O${}_7$ single crystal in high magnetic fields
• Successive magnetic transitions of Ca${}_2$CoSi${}_2$O${}_7$ in high magnetic fields