HoCrO3 and YCrO3: a comparative study.

A comparative study on structural, optical and magnetic properties of orthorhombic perovskite-like isostructural compounds HoCrO3 and YCrO3 was carried out, wherein Ho(3(+)) is a magnetic ion and Y(3+) is non-magnetic. We found almost identical structural parameters for both compounds, however a significant difference was observed in low wavenumber Raman active phonon modes. The effect of local field on optical transitions of Cr ion is studied by diffused reflectance spectroscopy. In order to understand the effect due to the Ho(3(+)) local magnetic field on the magnetic ordering of Cr(3(+)) in ACrO3 (A=Ho, Y), dc magnetization measurements were carried out in a temperature range of 5-300 K and several isotherms were analyzed. Magnetization measurements reveal that Cr(3+) magnetic ordering temperature is insensitive to local fields (due to Ho(3+)) and very sensitive to thermal cycling in the presence of an external applied magnetic field. This behavior is related to magnetic disorder near the phase transition due to weak ferromagnetism and/or structural distortions which we observed as thermal hysteresis. The importance of this work lies with the fact that both Ho(3+) (10.6 μB) and Y(3+) (0 μB) have identical ionic radii and the electron correlation effects in both the systems have been studied using different experimental techniques.