Magnetocaloric properties of TbCrO3 and TmCrO3 and their comparison with those of the other RCrO3 systems (R = Gd, Dy, Ho, and Er)

Magnetocaloric properties of TbCrO3 and TmCrO3 are reported and compared with those of the previously reported rare-earth chromites RCrO3 (R = Gd, Dy, Ho, and Er) and other perovskite-type oxides. The samples of TbCrO3 and TmCrO3 in this work were synthesized using a citrate gel combustion technique, and their magnetic properties were investigated and compared with those reported previously on RCrO3 (R = Gd, Dy, Ho, and Er). The Cr3+-Cr3+ ordering temperatures were found to strongly depend on the ionic radii of the rare-earth. By fitting the dc magnetization data with modified Curie-Weiss law including the Dzyaloshinsky-Moriya antisymmetric exchange interaction (D) and the symmetric exchange constant J(e), spin canting angles (alpha) were obtained. In general, alpha was found to increase with the decreasing ionic radii of R3+ in RCrO3. The magnetocaloric properties investigated included the magnetic entropy change (-Delta S) for a given change in magnetic field (Delta H), the corresponding adiabatic temperature change (Delta T-ad), and their relative variations (Delta T-ad/Delta H) and (-Delta S/Delta H). It is observed that for RCrO3, (-Delta S) measured in the vicinity of the ordering temperature of R3+-R3+, varies almost as G(2/3) where G is the de Gennes factor. Among RCrO3, GdCrO3 shows the largest value of (-Delta S/Delta H), because of its largest G factor and its magnitudes of (Delta T-ad/Delta H) and (-Delta S/Delta H) compare well with the reported values for the perovskites GdFeO3 and EuTiO3. These comparisons presented here provide useful information on the potential use of these materials in magneto-refrigeration technology.

Automated summary

The magnetocaloric properties of TbCrO3 and TmCrO3 were investigated and compared with other rare-earth chromites and perovskite-type oxides. The study found that the ordering temperatures of Cr3+-Cr3+ strongly depend on the ionic radii of the rare-earth. Additionally, the results suggest that GdCrO3 has potential applications in magneto-refrigeration technology.