Studium krystalových, elektronových a magnetických vlastností nově syntetizovaných vzácno-zeminných A2Ir2O7

Hájek, Filip

The A2Ir2O7 pyrochlores (A = Y, Pr-Lu) form an attractive family of compounds for their complex electronic properties and ground states, stemming from comparable strength of spin-orbit coupling and electron correlations on a geometrically frustrated lattice. The present thesis focusses on the study of crystallographic, electronic and mag- netic properties of two representatives of the series: Nd2Ir2O7 and Ho2Ir2O7. We syn- thesised single crystals of these materials using a new PbF2 flux method. Structure of the single crystals was studied employing single crystal X-ray diffraction. The pyrochlore structure was confirmed in Ho2Ir2O7 and a new non-pyrochlore structure, disordered tetragonal structure, was discovered in Nd2Ir2O7-like analogue. Physical properties of these compounds were investigated by magnetisation and specific heat measurements, indicating multiple magnetic transitions related to both Ir and A sublattices. The re- sults were discussed in the framework of previous results on A2Ir2O7 pyrochlores with a focus on Nd2Ir2O7 and Ho2Ir2O7. For the Nd2Ir2O7-like compound, we scrutinized similarities/differences with pyrochlore Nd2Ir2O7, namely magnetic properties of the two crystallographic variants.

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