Magnetic excitations in Er2Zr2O7 and Er2Ir2O7

The rare-earth oxides of the general formula A2B2O7, with A being a rare-earth ion (Er in our case) and B a d- or p-metal (B = Zr or Ir), have been extensively studied for their frequently exotic electronic properties. The majority of A2B2O7 crystallizes in cubic structure of ordered pyrochlore-type and disordered defect-fluorite-type. Former structure is a prototype of a geometrically frustrated structure while the magnetic frustration in latter one origins not only in the lattice, but also in disorder (A and B elements share the same crystallographic site). Event though global structures are different, our recent experiments showed strikingly similar low-temperature properties of Er2B2O7 compounds. The investigation of INS spectra of both analogues is believed to bring new results on their magnetic properties as well as shed more light on Er local structure in zirconate and iridiate.