Fig. 3: Magnetic susceptibility amplitude and local susceptibility.
From: Gapped commensurate antiferromagnetic response in a strongly underdoped model cuprate superconductor
a Magnetic susceptibility amplitude \(\chi^{\prime\prime}_0\), determined from 2D fits to background-subtracted data such as those in Fig. 2a. Filled circles: Ei = 70 meV. Open circles: Ei = 200 meV. b Difference between \(\chi^{\prime\prime}_0\) at 5 K, deep in the superconducting state, and at 70 K (black) and 410 K (yellow). c Local (momentum-integrated) susceptibility \({\chi}^{\prime\prime}_{\mathrm{loc}}\) (same colors and symbols as in (a)). d Difference in \({\chi}^{\prime\prime}_{\mathrm{loc}}\), using the same colors and symbols as (c). Black vertical bars in all panels: energies where DFT indicates phonon modes at qAF. At 410 K, the local maxima in \({\chi}^{\prime\prime}_0\) and \({\chi}^{\prime\prime}_{\mathrm{loc}}\) at ~30 and ~50 meV correspond to phonon crossings and indicate the inability of our analysis to completely remove unwanted phonon contributions and/or to discern an enhanced magnetic response due to nontrivial electron-lattice coupling effects at these energies. The small enhancement in \(\chi^{\prime\prime}_0\) near 30 meV across Tc = 55 K is consistent with the existence of a small magnetic resonance, but also coincides with phonon crossings, and hence may be an electron-lattice-coupling effect or spurious. Solid lines: guides to the eye.
