Narayan Appathurai | Searcharxiv

arXiv2025

Structural Phase Separation and Enhanced Superconductivity in La1.875Ba0.125CuO4 under Uniaxial Strain

Strain engineering has attracted significant attention in recent years due to its capability in tuning lattice and electronic structures of quantum materials. Using moderate uniaxial compressive strain, we induce structural phase separation in the low-temperature phase of x=1/8 La2-xBaxCuO4 (LBCO) single crystals. These structures are low temperature tetragonal (LTT), low temperature less orthorhombic (LTLO), and a plastically deformed nano-domain structure (PDNS), comprised of few-nanometer-sized orthorhombic domains within an amorphous matrix. These three structures exhibit distinct superconducting behaviors. The volume fraction of the LTT structure is suppressed with increasing strain, while its superconducting transition temperature increases and broadens. The LTLO structure exhibits a sharp superconducting transition above 32 K, which increases up to ~36 K at maximum strain. The PDNS phase exhibits a very broad superconducting transition and persists even after removing the strain. Our study illustrates the sensitivity of superconductivity to the structure of the LBCO sample near its stripe instability.

cond-mat.supr-con↗

arXiv2024

Investigating the Limits of Hard X-ray Coherence Length Measurement Employing Young's Double Slit Experiment

Young's double slit experiment has been the most explored technique to gauge the coherence properties of a given system. The limits of this technique in characterizing spatial coherence properties of high emittance, hard x-ray synchrotron sources have been performed at the BXDS-IVU beamline, Canadian Light Source (CLS). High emittance synchrotron sources have always been assumed to possess sub-optimal coherence properties, especially in the hard X-ray regime. While this is largely true, it is very important to understand the limits of coherence for these existing high emittance sources. We have demonstrated that the Young's double slit experiment has harsher limits than what is normally expected in the form of inherent ambiguity. We present data obtained at multiple energies in both the horizontal and vertical direction leading to a thorough understanding of the fundamental limitations of employing Young's double slit experiment to characterize inherently low coherence length systems. We have put forth a novel numerical technique to estimate the source size directly from the Young's double slit interference patterns. With these results, we have demonstrated that CLS has functional coherent beam properties in the hard X-ray regime with Spatial coherence lengths ranging from 5.37$\mu \text{m}$ to 17.61$\mu \text{m}$ in the horizontal direction. The same in the vertical direction was at least 3 times larger. Finally, we present theoretical calculations showcasing the limits of Young's double slit experiment in characterizing diffraction limited sources.

physics.optics↗