Low-temperature properties of pyrochlore Lu2Ir2O7

Magnetic properties and crystal field splitting of the rare-earth pyrochlore Er2Ir2O7

“…ρ is the diagonal density matrix with exponentials e [7,8]. We note that such an anomaly in specific heat was not observed previously, at least on heavy rare-earth pyrochlores, except our recent study on Lu 2 Ir 2 O 7 [15]. (Such observation might point to the high quality of our sample.)…”

“…The determined CF eigenenergies and parameters were used to describe our specific-heat and magnetization data leading to an excellent agreement between experiment and CF calculations. Furthermore, our new bulk data (utilizing also our previous results on Lu 2 Ir 2 O 7 [15]) allowed us to identify the temperature of Ir the magnetic (shortor long-range) ordering/MIT transition, T MIT = 140 K. The low-temperature data then strongly suggest a short-range order among Er cations below T LT = 2 K.…”

“…AIAO ordering of the Ir sublattice and glassy freezing of Er 3+ moments at low temperatures were suggested for Er 2 Ir 2 O 7 [9]. Concluding our short list, the investigation of Lu 2 Ir 2 O 7 with nonmagnetic Lu 3+ brought information on magnetic properties of the Ir sublattice not influenced by rare-earth magnetism, suggesting short-range correlations rather than long-range ordering of iridium moments [10,15].…”

“…Assuming the anomaly is connected to magnetic contribution of the iridium sublattice to specific heat, we estimated its entropy to be S Ir = 0.38 J K -1 mol -1 . In order to do so, the high-temperature specific-heat data were fitted by a smooth curve and subtracted from total specific heat, in the same way as previously done for Lu 2 Ir 2 O 7 [15]. Comparing the calculated entropies of both analogs, the lutetium iridate (S Ir = 0.57 J K -1 mol -1 ) anomaly is connected with slightly higher entropy.…”

“…Such ordering is supported by magnetization measurements [a bifurcation of zero-field cooled (ZFC) and field cooled (FC) magnetization curves] [8][9][10], local muon spin-resonance technique [11][12][13], or neutron-diffraction experiments [14]. However, short-range correlations between Ir 4+ magnetic moments, rather than their long-range ordering, have also been proposed [15][16][17] to explain the experimental data, particulary due to low magnetic moment on Ir. The short-/long-range magnetic ordering of the Ir sublattice is often discussed also with respect to the change of conducting properties.…”