Evidence of active role played by the nonmagnetic element Sr in magnetostructural coupling inSrRuO3

Abstract

We study the magnetic transition in SrRuO 3 , the only itinerant 4d ferromagnet, employing x-ray absorption fine structure study and state-of-the-art band-structure calculations. Both experimental and theoretical results reveal an unusual evolution of the local structural parameters around the spectator element, Sr, across the magnetic transition. Interestingly, such evolution of the Sr-related bonds nucleate at a temperature, T Ã , higher than the magnetic transition temperature, indicating the presence of a precursor effect. Contrary to common belief, these results point to the active role played by the Sr ion in the magnetostructural coupling present in this compound.

Electronic structure of RuSr2EuCu2O8studied by x-ray absorption and photoemission spectroscopies

“…Indeed, it has been observed that the nonmagnetic Sr ion played an important role in magnetic transition in SRO. 38 This paper suggests that WFM and SC be accompanied by a significant decrease of local distortions of Cu-Sr and Ru-Sr bonding in RuEu-1212. In order to understand the details of how the dynamic local lattice distortions affect the SC and WFM properties of RuEu-1212, progressive data analysis of the evolution of the local atomic structure with the decrease of the temperature has been underway.…”

Assessing the feasibility of low temperature XAFS experiments at Indus-2, India: First results

“…The minimum temperature step size, for low temperature-dependent XAFS experiments, is determined to be ΔT ¼ 5 K. We expect the calibration to be as good for metallic samples in general. For insulating samples, adequate temperature accuracy can be attained if thin and uniform samples (on tape/pellets) are sandwiched between the plates of Cu sample holder [5][6]11,25,42]. 1 Following this first report of commissioning low temperature XAFS facility at Indus-2, we plan to pursue lower (o50 K) temperature-XAFS of non-standard samples in the future.…”

“…(ii) XAFS, being element-specific probe, can extract well-resolved structural information around different sites separately [16][17][18][19][20]. Low temperature XAFS experiments have gained impetus over the years, due to the growing importance of understanding short-rangeorder (SRO) changes across magneto-electronic phase transitions that generally occur at low temperature (T c o o300 K) [8,[21][22][23][24][25]. For example, in Ref.…”

“…Most of the phase transitions of our current interest occur in the temperature range 50-250 K [e.g. spintronic material [25,[29][30][31]; Fe-based superconductors (T c $ 55 K) [32,33], spin glass YBaCo 4 O 7 (T c ¼ 65 K) [34,35],half-metallic CeMnNi 4 (T c ¼ 140 K) [6]. Correspondingly, we have selected standard Au foil for feasibility test and standardization, since Au L3 XAFS shows significant and standardized DWF evolution [σ 2…”

First phase commissioning of high pressure XAFS setup at ED-XAFS beamline, Indus-2 synchrotron radiation source, India

“…1a-c. Information of each near neighbor bond is derived from the analysis of each peak in χ(R); broadly, peak position, amplitude and width respectively correspond to bond-length (R), coordination number N and bond distribution (Debye Waller factor or DWF) [2]. Being electron wave scattering phenomenon, XAFS information is inherently local in nature and hence can be used for studying local-scale defects [3][4][5]. Over the years, understanding of local-scale defects (for example, their role on electronic structure) has gained importance, as long-range-order (LRO) could not adequately explain many of the phase transitions [6][7][8][9][10][11].…”