Implications of magnetic and magnetodielectric behavior of GdCrTiO5.

We have carried out dc magnetization, heat-capacity, and dielectric studies down to 2K for the compound GdCrTiO₅, crystallizing in orthorhombic Pbam structure, in which well-known multiferroics RMn₂O₅ (R=Rare-earths) form. The points of emphasis are: (i) The magnetic ordering temperature of Cr appears to be suppressed compared with that in isostructural Nd counterpart, NdCrTiO₅. This finding on the Gd compound suggests that Nd 4f hybridization plays an uncommon role in the magnetism of Cr in contrast to a proposal long ago. (ii) Dielectric constant does not exhibit any notable feature below about 30K in the absence of external magnetic field, but a peak appears and gets stronger with the application of external magnetic fields, supporting the existence of magnetodielectric coupling. (iii) The dielectric anomalies appear even near 100 K, which can be attributed to short-range magnetic-order. We also observe a gain in spectral weight below about 150K in Raman spectra in the frequency range 150-400 cm^-1, which could be magnetic in origin, supporting short-range magnetic order. It is of interest to explore whether geometrically frustration plays any role in the dielectric properties of this family, as in the case of RMn₂O₅. [ABSTRACT FROM AUTHOR]