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Magnetic properties of rare-earth A2Ir207 pyrochlore iridates
Vlášková, Kristina ; Klicpera, Milan (advisor) ; Kempa, Martin (referee) ; Sibille, Romain (referee)
The present thesis is focused on the synthesis, characterisation and magnetic properties of A2Ir2O7 pyrochlore iridates with A standing for Dy - Lu. The geometrically frustrated pyrochlore lattice affects the interactions between magnetic moments of both A3+ and Ir4+ , frequently leading to complex low-temperature states. Moreover, an interplay between spin-orbit coupling and electron correlations, inherent to iridium ions, has been proposed/observed to significantly affect the conductive properties of pyrochlores. The A2Ir2O7 iridates were synthesized, and respective synthesis routes optimized, by CsCl flux method. Thoroughly characterised samples, including previously unprepared A = Tm analogue, were investigated by means of standard bulk methods, as well as techniques of neutron scattering and muon spin resonance. An evolution of magnetic ordering of the iridium sublattice was followed for heavy rare-earth part of the series, allowing to finalize the respective phase diagram. An emergence of oscillations in muon spin rotation spectra unambiguously proved the existence of long-range iridium ordering in studied members. The dynamical AC susceptibility response was discussed in the frame of the model considering weakly bounded spins at the antiferromagnetic domain walls in the material, which appears to be...
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