Visualization of spatial inhomogeneity in the superconducting gap using micro-ARPES

Electronic inhomogeneity arises ubiquitously as a consequence of adjacent and/or competing multiple phases or orders in strongly correlated electron systems. Gap inhomogeneity in high- <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>T</mml:mi> <mml:mi>c</mml:mi></mml:mrow> </mml:math> cuprate superconductors has been widely observed using scanning tunneling microscopy/spectroscopy. However, it has yet to be evaluated by angle-resolved photoemission spectroscopy (ARPES) due to the difficulty in achieving both high energy and spatial resolutions. Here, we employ high-resolution spatially-resolved ARPES with a micrometric beam (micro-ARPES) to reveal the spatial dependence of the antinodal electronic states in optimally-doped Bi <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi> </mml:mi> <mml:mn>2</mml:mn></mml:math> Sr <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi> </mml:mi> <mml:mn>2</mml:mn></mml:math> CaCu <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi> </mml:mi> <mml:mn>2</mml:mn></mml:math> O <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi> </mml:mi> <mml:mrow><mml:mn>8</mml:mn> <mml:mo>+</mml:mo> <mml:mi>δ</mml:mi></mml:mrow> </mml:math> . Detailed spectral lineshape analysis was extended to the spatial mapping dataset, enabling the identification of the spatial inhomogeneity of the superconducting gap and single-particle scattering rate at the micro-scale. Moreover, these physical parameters and their correlations were statistically evaluated. Our results suggest that high-resolution spatially-resolved ARPES holds promise for facilitating a data-driven approach to unraveling complexity and uncovering key parameters for the formulation of various physical properties of materials.