Magnetic properties of RE2Mo2O7 pyrochlores

The magnetic properties of RE₂Mo₂O₇ (RE=Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, and Yb³⁺) and of solid solutions of the type (Nd_1?x A _x )₂Mo₂O₇ (A=Yb or Er; 0.05≤x≤0.4) have been studied using an ac mutual inductance bridge. All the compounds were found to exhibit magnetic ordering in the neighborhood of or below 77 K. The data have been analyzed using (i) the available susceptibility data on Y₂Mo₂O₇, (ii) a ferromagnetic coupling among the Mo⁴⁺ ions to obtain the contribution from the RE³⁺ ion, and (iii) the available susceptibility data on RE₂Ti₂O₇ to obtain the contribution from the Mo⁴⁺ ions. It was found that procedure (iii) gave the most satisfactory explanation of the magnetic ordering. The results indicated that (1) the Mo⁴⁺ ions become ordered magnetically, (2) the behavior of the RE³⁺ ions is almost the same as in the isostructural RE₂Ti₂O₇ and RE₂V₂O₇ compounds, and (3) the susceptibility values differ appreciably as we go from Nd³⁺ to Yb³⁺, possibly due to narrowing of the π* Mo-O conduction band.