Abstract
X-ray scattering (XRS), x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectroscopic techniques were used to study the electronic and atomic structures of the high-quality Sr3Ir4Sn13 (SIS) single crystal below and above the transition temperature (T* ≈ 147 K). The evolution of a series of modulated satellite peaks below the transition temperature in the XRS experiment indicated the formation of a possible charge density wave (CDW) in the (110) plane. The EXAFS phase derivative analysis supports the CDW-like formation by revealing different bond distances [Sn1(2)-Sn2] below and above T* in the (110) plane. XANES spectra at the Ir L3-edge and Sn K-edge demonstrated an increase (decrease) in the unoccupied (occupied) density of Ir 5d-derived states and a nearly constant density of Sn 5p-derived states at temperatures T < T* in the (110) plane. These observations clearly suggest that the Ir 5d-derived states are closely related to the anomalous resistivity transition. Accordingly, a close relationship exists between local electronic and atomic structures and the CDW-like phase in the SIS single crystal.
Highlights
Temperature-dependent x-ray scattering (XRS) has been frequently used to verify that the series of satellite peaks associated with charge modulation are related to the charge density wave (CDW) phenomena in certain orientations[21,29,30,31]
Little is known about the contributions of the constituent elements, including Ir and Sn, to the phase transition that is significantly associated with the CDW property in a SIS single crystal
A high-quality single crystal of SIS is examined in detail using XRS, x-ray absorption near-edge structure (XANES), extended x-ray absorption fine structure (EXAFS) and resistivity measurements at various temperatures
Summary
To complex bond distances, the phase function Ψ(k) and the phase derivative dΨ(k)/dk of the Sn K-edge EXAFS spectra were obtained and are presented in Fig. 4(a,b) for the E-field parallel and perpendicular to the (110) plane, respectively. In experiments that involve synchrotron radiation, a series of satellite peaks, structural distortion at the Sn sites and a decrease (an increase) in the number of occupied (unoccupied) Ir 5d-derived states parallel to the (110) plane were demonstrated at T < T*. These results support the CDW modulation in the SIS single crystal at T < T*. This study demonstrates significant anisotropy in the electronic and atomic structures of a single crystal of SIS at various temperatures by comparing the XRS, XANES and EXAFS spectra
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