RESUMO
Resonant inelastic X-ray scattering (RIXS) is an extremely valuable tool for the study of elementary, including magnetic, excitations in matter. The latest developments of this technique have mostly been aimed at improving the energy resolution and performing polarization analysis of the scattered radiation, with a great impact on the interpretation and applicability of RIXS. Instead, this article focuses on the sample environment and presents a setup for high-pressure low-temperature RIXS measurements of low-energy excitations. The feasibility of these experiments is proved by probing the magnetic excitations of the bilayer iridate Sr3Ir2O7 at pressures up to 12â GPa.
RESUMO
The high brilliance of modern synchrotron radiation sources facilitates experiments with high-energy x-rays across a range of disciplines, including the study of the electronic and magnetic correlations using elastic and inelastic scattering techniques. Here we report on Nuclear Resonance Scattering at the 73 keV nuclear level in 193Ir. The transitions between the hyperfine split levels show an untypically high E2/M1 multi-polarity mixing ratio combined with an increased sensitivity to certain changes in the hyperfine field direction compared to non-mixing transitions. The method opens a new way for probing local magnetic and electronic properties of correlated materials containing iridium and provides novel insights into anisotropic magnetism in iridates. In particular, unexpected out-of-plane components of magnetic hyperfine fields and non-zero electric field gradients in Sr2IrO4 have been detected and attributed to the strong spin-orbit interaction in this iridate. Due to the high, 62% natural abundance of the 193Ir isotope, no isotopic enrichment of the samples is required, qualifying the method for a broad range of applications.
RESUMO
A polycrystalline sample of SrLa2FeCoSbO9 has been prepared in a solid-state reaction and studied by a combination of electron microscopy, magnetometry, Mössbauer spectroscopy, X-ray diffraction, and neutron diffraction. The compound adopts a monoclinic (space group P21/ n; a = 5.6218(6), b = 5.6221(6), c = 7.9440(8) Å, ß = 90.050(7)° at 300 K) perovskite-like crystal structure with two crystallographically distinct six-coordinate sites. One of these sites is occupied by 2/3 Co2+, 1/3 Fe3+ and the other by 2/3 Sb5+, 1/3 Fe3+. This pattern of cation ordering results in a transition to a ferrimagnetic phase at 215 K. The magnetic moments on nearest-neighbor, six-coordinate cations align in an antiparallel manner, and the presence of diamagnetic Sb5+ on only one of the two sites results in a nonzero remanent magnetization of â¼1 µB per formula unit at 5 K.
RESUMO
A polycrystalline sample of La3Ni2SbO9 has been synthesized using a standard ceramic method and characterized by neutron diffraction and magnetometry. The compound adopts a monoclinic, perovskite-like structure with space group P2(1)/n and unit cell parameters a = 5.0675(1), b = 5.6380(1), c = 7.9379(2) Å, ß = 89.999(6)° at room temperature. The two crystallographically distinct six-coordinate sites are occupied by Ni(2+) and a disordered distribution of Ni(2+)/Sb(5+), respectively; the Ni(2+) and Sb(5+) cations occupy the disordered site in a 1:2 ratio. Both ac and dc magnetometry indicate the presence of a spontaneous magnetization below 105 K. A magnetization of 1.5 µB per formula unit was measured at 2 K in a field of 40 kOe. However, no magnetic scattering was observed in neutron diffraction data collected at 5 K. It is proposed that, as a consequence of the cation disorder, La3Ni2SbO9 behaves as a relaxor ferromagnet, analogous to a relaxor ferroelectric, with magnetic domains too small to be detected by neutron diffraction forming below 105 K.
