ausblenden:
Schlagwörter:
Chromium compounds, Crystal growth, Crystal impurities, Ground state, Magnetism, Potassium compounds, Specific heat, Temperature, X ray absorption spectroscopy, Heat data, Hydroxide fluxes, Low-temperature specific heat, Magnetic impurity, Paramagnetic behavior, Polycrystalline, Single crystal growth, Space Groups, Type structures, X-ray absorption spectroscopy, Single crystals
Zusammenfassung:
Single crystals of Sr3NaIrO6 and Sr3AgIrO6 have been successfully grown using hydroxides flux. Sr3NaIrO6 and Sr3AgIrO6 crystallize in the K4CdCl6-type structure with the space group R-3c (no. 167). Sr3NaIrO6 and Sr3AgIrO6 are electrically insulating with estimated activation gaps of 0.68 and 0.80 eV, respectively. Sr3NaIrO6 and Sr3AgIrO6 show paramagnetic behavior down to 2 K. In this work, the observed effective moments, μeff, for Sr3NaIrO6 single crystals are 0.31μB for H⊥c and 0.28μB for H||c, which are much smaller than that of 0.49μB previously reported for the polycrystalline Sr3NaIrO6 samples. For Sr3AgIrO6 single crystals, a much larger value of μeff=0.57μB is observed as compared with Sr3NaIrO6 single crystals. The x-ray absorption spectroscopy and low-temperature specific heat data indicate that the Ir in Sr3NaIrO6 has an almost pure Ir5+ valence state, while the Ir in Sr3AgIrO6 is slightly lower than +5. The estimated low limits of magnetic impurity Ir4+ are about ∼1.7% and ∼9.2% for Sr3NaIrO6 and Sr3AgIrO6, respectively. These magnetic impurities are likely to fully explain the observed μeff values for Sr3NaIrO6 and Sr3AgIrO6 single crystals, supporting the J=0 ground state of Ir5+ in Sr3NaIrO6 and Sr3AgIrO6. © 2022 American Physical Society.
