Magnetic manifestations from the application of perturbations on the dynamic spin ice Pr2Sn2O7
Sarte, Paul Maximo
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The purpose of this study was to investigate the effects of two perturbations, the application of an external magnetic field and randomised chemical pressure through Ti4+/Sn4+ substitution, on the dynamic spin ice state in Pr2Sn2O7. We show through magnetometry, heat capacity and powder neutron diffraction that the dynamic spin ice state in Pr2Sn2O7 is extremely fragile, requiring an external field of approximately 0.5 T to induce a transition into a long range ordered antiferromagnetic state, in accordance with the recorded behaviour of other spin ice materials. Similarly, the dynamic spin ice state in Pr2Sn2O7 only required a doping percentage of less than 2.5% to induce a transition away from the spin ice state. But instead of the predicted spin glass state, Pr2Sn2O7 assumes a cluster-type magnetic structure with extremely weak intercluster antiferromagnetic interactions, a magnetic structure that persists even to the highest doping level of 30%. The results of this thesis reveals that careful attention must be taken when selecting and placing the tetravalent cation in the 16c Wyckoff site in the pyrochlore structure, if one desires to have a spin ice state.