Dielectric and polarization measurements of the noncentrosymmetric “114” cobaltite CaBaCo${}_4$O${}_7$ were carried out on polycrystalline pellets. Our results show that this material exhibits a clear dielectric peak at $T_C$ and polarization in the ferrimagnetic state below $T_C$ = 70 K. The ferroelectric nature of this phase is supported by pyroelectric measurements. It is shown that this multiferroic material exhibits a magnetodielectric effect of 16$\%$ under 14 T just below $T_C$. In the absence of any structural transition in the whole temperature range (300–4 K), the emergence of polarization at $T_C$ suggests that the ferrimagnetic ordering induces or assists the ferroelectricity. The symmetry analysis shows that in the magnetic phase the Heesch-Schubnikov point group is $m^{\prime }m{2}^{\prime }$, which offers a unique potential for the possible coexistence of ferroelectricity, ferromagnetism, and ferrotoroidicity in this compound along three directions oriented at 90°.

• Received 19 September 2011

DOI:https://doi.org/10.1103/PhysRevB.86.024410