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arXiv · 1107.5021

Nodal quasiparticle meltdown in ultra-high resolution pump-probe angle-resolved photoemission

J. Graf·C. Jozwiak·C. L. Smallwood·H. Eisaki·R. A. Kaindl·D. -H. Lee·A. Lanzara
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Abstract

High-$T_c$ cuprate superconductors are characterized by a strong momentum-dependent anisotropy between the low energy excitations along the Brillouin zone diagonal (nodal direction) and those along the Brillouin zone face (antinodal direction). Most obvious is the d-wave superconducting gap, with the largest magnitude found in the antinodal direction and no gap in the nodal direction. Additionally, while antinodal quasiparticle excitations appear only below $T_c$, superconductivity is thought to be indifferent to nodal excitations as they are regarded robust and insensitive to $T_c$. Here we reveal an unexpected tie between nodal quasiparticles and superconductivity using high resolution time- and angle-resolved photoemission on optimally doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$. We observe a suppression of the nodal quasiparticle spectral weight following pump laser excitation and measure its recovery dynamics. This suppression is dramatically enhanced in the superconducting state. These results reduce the nodal-antinodal dichotomy and challenge the conventional view of nodal excitation neutrality in superconductivity.

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J. Graf, C. Jozwiak, C. L. Smallwood, H. Eisaki, R. A. Kaindl, D. -H. Lee, A. Lanzara. 2011-07-25. Nodal quasiparticle meltdown in ultra-high resolution pump-probe angle-resolved photoemission. https://doi.org/10.1038/nphys2027

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