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We present a laser reaction chamber that we have developed for in situ/operando X‐ray diffraction measurements at the NSLS‐II 28‐ID‐2 X‐ray powder diffraction beamline. This chamber allows for rapid and dynamic sample heating under specialized gas environments, spanning ambient conditions down to vacuum pressures. We demonstrate the capabilities of this setup through two applications: laser‐driven heating in polycrystalline iron oxide and in single‐crystal WTe2. Our measurements reveal the ability to resolve chemical reaction kinetics over minutes with 1 s time resolution. This setup advances opportunities for in situ/operando X‐ray diffraction studies of both bulk and single‐crystal materials. A laser reaction chamber has been developed for in situ/operando X‐ray diffraction measurements on the NSLS‐II 28‐ID‐2 beamline, allowing for rapid sample heating under various gas and vacuum conditions. This capability has enabled the tracking of chemical reaction kinetics in polycrystalline iron oxide and a reversible phase transformation in WTe2 with 1 s time resolution, expanding the opportunities for dynamic studies in both bulk and single‐crystal materials.

The electron-doped material Nd$_{2-x}$Ce$_x$CuO$_4$ becomes superconducting with a Ce$^{4+}$ composition around 0.16, but only after removal of a minuscule amount of extraneous oxygen. This enigmatic behavior was addressed here. A small fraction of copper in the CuO$_2$ planes of Nd$_{2-x}$Ce$_x$CuO$_4$ was substituted by cobalt-57, which serves as a microprobe of the chemical environment. Deoxygenation brought about little change in the Mossbauer spectra both above and below the optimal superconducting concentration; however, for x = 0.16 a change was observed. In the latter, a major fraction of the magnetically split, five-coordinate species showed itself as a paramagnetically relaxed doublet upon deoxygenation. The abundance of the paramagnetically relaxed species corresponds closely to the diamagnetic volume fraction and thus provides a microscopic signature of the superconducting phase.

We present a laser reaction chamber that we developed for in-situ/operando X-ray diffraction measurements at the NSLS-II 28-ID-2 XPD (X-Ray Powder Diffraction) beamline. This chamber allows for rapid and dynamic sample heating under specialized gas environments, spanning ambient conditions down to vacuum pressures. We demonstrate the capabilities of this setup through two applications: laser-driven heating in polycrystalline iron oxide and in single crystal WTe2. Our measurements reveal the ability to resolve chemical reaction kinetics over minutes with 1-s time resolution. This setup advances opportunities for in-situ/operando XRD studies in both bulk and single crystal materials.

YBa\\(_2\\)Cu\\(_3\\)O\\(_7-\\) (YBCO) has favorable macroscopic superconducting properties of \\(T_c\\) up to 93 K and \\(H_c2\\) up to 150 T. However, its nanoscale electronic structure remains mysterious because bulk-like electronic properties are not preserved near the surface of cleaved samples for easy access by local or surface-sensitive probes. It has been hypothesized that Ca-doping at the Y site could induce an alternate cleavage plane that mitigates this issue. We use scanning tunneling microscopy (STM) to study both Ca-free and 10% Ca-doped YBCO, and find that the Ca-doped samples do indeed cleave on an alternate plane, yielding a spatially-disordered partial (Y,Ca) layer. Our density functional theory calculations support the increased likelihood of this new cleavage plane in Ca-doped YBCO. On this surface, we image a superconducting gap with average value 24 \\(\\) 3 meV and characteristic length scale 1-2 nm, similar to Bi-based high-\\(T_c\\) cuprates, but the first map of gap inhomogeneity in the YBCO family.

We report measurements of NMR spin-lattice (T sub(1)) and spin-spin (T sub(2)) relaxation times for super(89)Y in the parent structure of the electron-doped copper-oxide superconductors. T sub(1) data exhibit non-exponential recovery with T sub(1) approximately 20 s. T sub(2) decreases rapidly with temperature above the Neel temperature, but remains constant above 425 K. We discuss these behaviors by considering fluctuating antiferromagnetic spin clusters associated with oxygen defects.

We report the effect of oxygen pressure during growth (\\(P_{O_{2}}\\)) on the electronic and magnetic properties of PrAlO\\(_3\\) films grown on \\(\\rm TiO_{2}\\)-terminated SrTiO\\(_3\\) substrates. Resistivity measurements show an increase in the sheet resistance as \\(P_{O_{2}}\\) is increased. The temperature dependence of the sheet resistance at low temperatures is consistent with Kondo theory for \\(P_{O_{2}} \\ge 10^{-5}\\) torr. Hall effect data exhibit a complex temperature dependence that suggests a compensated carrier density. We observe behavior consistent with two different types of carriers at interfaces grown at \\(P_{O_{2}} \\ge 10^{-4}\\) torr. For these interfaces, we measured a moderate positive magnetoresistance (MR) due to a strong spin-orbit (SO) interaction at low magnetic fields that evolves into a larger negative MR at high fields. Positive high MR values are associated with samples where a fraction of carriers are derived from oxygen vacancies. Analysis of the MR data permitted the extraction of the SO interaction critical field ( e.g. \\( H_{SO}=\\)1.25 T for \\(P_{O_{2}}=10^{-5}\\) torr). The weak anti-localization effect due to a strong SO interaction becomes smaller for higher \\(P_{O_{2}}\\) grown samples, where MR values are dominated by the Kondo effect, particularly at high magnetic fields.

We report NMR lineshape, spin-lattice relaxation time T1, and spin-spin relaxation time T2 data at 17 MHz (8.07 T) for 89Y in the copper-oxide spin-chain compound Ca2+xY2-xCu5O10. For x = 0, a broad, asymmetric line with width *Dv #~ 90 kHz is observed for T = 250-300 K. The spectra exhibit an appreciable average shift (*DH/H fa +0.7%) and sharpen at lower temperature, possibly due to increasing intrachain ferromagnetic correlations. T1 and T2 decrease with decreasing temperature. The T1 data imply a short correlation-time limit, with *te = 3-5 x 10-11 s. The T2 data apparently include a contribution from dipolar interactions with copper nuclei. Relaxation time data for a doped (x = 0.5) compound surprisingly show more rapid relaxation.

The adiabatic condition governing cyclic adiabatic inversion of proton spins in a micron-sized ammonium chloride crystal was studied using room temperature nuclear magnetic resonance force microscopy. A systematic degradation of signal-to-noise was observed as the adiabatic condition became violated. A theory of adiabatic following applicable to cyclic adiabatic inversion is reviewed and implemented to quantitatively determine an adiabaticity threshold \\((\\gamma H_1)^2/(\\omega_{osc}\\Omega) = 6.0\\) from our experimental results.