Investigation of the magnetic properties ofY2Ru2O7byRu

Abstract

Magnetic properties of the Mott insulator with the pyrochlore structure Y 2 Ru 2 O 7 were investigated using 99 Ru Mössbauer spectroscopy. Bulk magnetization measurements confirmed appearance of the spin-glass-like antiferromagnetic order with very large differences between zero-field-cooled and field-cooled magnetizations below the Néel temperature T N =76͑2͒ K. The Mössbauer spectra were obtained above and below T N . Analysis of the spectrum recorded at 4.2 K suggested a noncollinear local ordering of ruthenium magnetic moments. The electronic structure of the individual ruthenium ion, responsible for magnitudes of hyperfine parameters and the ruthenium magnetic moment, was discussed within the framework of the crystalline electric-field model, including the spin-orbit coupling and the exchange interaction in the molecular-field approximation. Reasonably good agreement between calculated and experimentally determined parameters was obtained. Simultaneously, the experimentally observed easy plane of ruthenium magnetic moments was explained. A. Sample preparation and characterizationPolycrystalline samples of Y 2 Ru 2 O 7 and Y 2 Ru 1.99 Sn 0.01 O 7 were prepared by the solid-state reaction from weighted in proper molar ratios mixtures of powders: Y 2 O 3 , RuO 2 , and enriched 119 SnO 2 . The mixtures were prereacted at 800°C for 12 h in air. After grinding they were pressed into pellets and sintered at 1150°C for 16 h in air. The grinding and sintering cycle was repeated several times. The x-ray-diffraction measurements were performed using Cu K␣ radiation in D501 Siemens powder diffractometer.

Structural disorder, magnetism, and electrical and thermoelectric properties of pyrochlore Nd2Ru2O7

“…While magnetic properties of Nd 2 Ru 2 O 7 have been reported previously [7], we show here that the presence of ferromagnetic impurity phases compromised the earlier analysis. There has also been some confusion in the literature about the nature of the ordering of the Ru 4d spins in Nd 2 Ru 2 O 7 ; several reports have suggested that the ordering is glassy [8,9,10,11,12]. We find compelling evidence that Nd 2 Ru 2 O 7 is not a spin-glass, and propose a reason for the observed history-dependence of the ZFC-FC magnetic susceptibility and weak ferromagnetism below the ordering temperature.…”

“…In particular, several reports have mentioned that the glassy nature of the ordering of Ru 4d spins is evident in bulk magnetic susceptibility measurements [8,9,10,11,12]. However, neutron diffraction experiments below the ordering temperature show that Ru spins order with a long correlation length [9,10].…”

Evolution of structure, magnetism, and electronic transport in the doped pyrochlore iridate Y2Ir2−xRuxO7

“…3 The decrease of SOC with Ru substitution will presumably drive the system toward more collinear type AFM spin structure, yet the Mossbauer spectroscopy experiments have shown another end compound i.e., Y 2 Ru 2 O 7 is still a non-collinear type AFM system. 25 Moreover, recent calculations have shown that with increasing U the magnetic state in Y 2 Ir 2 O 7 moves from non-collinear AIAO state to AFM spin structure. 13,14 Therefore, the decreasing moment with x in present study (see Figs.…”

Ruthenium-europium configuration in the Eu2Ru2O7 pyrochlore

“…8,9 Due to the usual nonmagnetic nature of the Eu 3+ ions, one would expect an intrinsic behaviour similar to that observed in the Y and Lu pyrochlores where no magnetic transitions occur at low temperatures. 10 This anomalous second magnetic transition has been systematically reported in the literature. [7][8] However, due to difficulties in performing neutron scattering experiments on Eu-based compounds, the precise nature of the observed ordering remains unknown.…”