A local study of the influence of annealing temperature that can provoke structural defects and chemical disorder on the magnetism of Heusler alloys has been carried out by measuring hyperfine interactions in Pd 2 MnZ ͑Z = Ge, In, Sn, and Sb͒. Perturbed angular correlation method has been used to measure the hyperfine fields at 111 Cd probe nuclei substituting the Mn and Z sites as a function of temperature. The fraction of 111 In-nuclei-occupying Mn sites was found to increase with the

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... g of sample at higher temperatures followed by quenching that can leave the alloy in a disordered state. As a consequence, it was possible to observe the effect of temperature in the ordering of the alloys. Moreover, electric quadrupole interaction measurements clearly indicated chemical disorder after quenching in Pd 2 MnSn and an improvement in the ordering of the Pd 2 MnGe structure at high temperatures.