Manifestation of the Magnetic Resonance Mode in the Nodal Quasiparticle Lifetime of the Superconducting Cuprates

Studying the nodal quasiparticles in superconducting cuprates by photoemission with highly improved momentum resolution, we show that a new “kink” feature in the scattering rate is a key to uncover the nature of electron correlations in these compounds. Our data provide evidence that the main doping independent contribution to the scattering can be well understood in terms of the conventional Fermi liquid model, while the additional doping dependent contribution has a magnetic origin. This sheds doubt on applicability of a phonon-mediated pairing mechanism to high-temperature superconductors.

Figure 1

Temperature dependence of the scattering rate for the nodal quasiparticles in optimally doped $(\mathrm{Bi},\mathrm{Pb}{)}_2{\mathrm{Sr}}_2{\mathrm{CaCu}}_2{\mathrm{O}}_{8-\delta }$. In (a), the FWHM of the MDCs of the photoemission intensity is shown for different temperatures as a function of the energy of the quasiparticles. The gray solid line represents a contribution from the usual Auger decay (Fermi liquid parabola) [1] obtained by fitting the data for the highly overdoped sample (OD69) at 130 K (see inset). (b) illustrates the result of a subtraction of the Fermi liquid parabola for each temperature in terms of the imaginary part of the self-energy (the $\mathrm{FWHM}/2$ is multiplied to the bare Fermi velocity $v_F=4\mathrm{eV}\AA$).

Figure 2

Evolution of the scattering rate kink with doping and temperature. The MDC width as a function of energy is presented for a selected number of temperatures for the superstructure-free Bi(Pb)-2212 and pure Bi-2212 samples of different doping levels from underdoped, $T_c=76\mathrm{K}$ (a), to overdoped, $T_c=73\mathrm{K}$ (d).

Figure 3

Strengthening of the scattering mode with underdoping. Comparison of the imaginary part of the self-energy of nodal quasiparticles in Bi(Pb)-2212 underdoped ($T_c=76\mathrm{K}$) and overdoped ($T_c=73\mathrm{K}$) samples at 25 K. The black solid line represents a contribution from the Fermi liquid parabola. The shaded areas represent the contributions from the magnetic scattering obtained by subtraction of the FL parabola.

Figure 4

Sharpening of the scattering rate kink with lowering temperature for double- and single-layer compounds. The panels show the data for temperatures below and above the superconducting transitions, as well as their difference for underdoped ($T_c=85\mathrm{K}$) Bi-2212 (a) and optimally doped ($T_c=32\mathrm{K}$) Bi(La)-2201 (b) [for Bi(La)-2201, the difference is multiplied by factor of 2].