Magnetic Resonant Excitations in High‐Tc Superconductors

Abstract

PAILHES, S.; KEIMER, B.; BOURGES, P.; ULRICH, C.; REGNAULT, L. P.; Phys. Status Solidi B 241 (2004) 6, 1204-1210; Lab. Leon Brillouin, CNRS, Cent. Etud. Saclay, F-91191 Gif-sur-Yvette, Fr.; Eng.) -Schramke 41-225

Magnetism and superconductivity driven by identical 4 f states in a heavy-fermion metal

“…However, the excitations be-come fully inelastic when entering the superconducting state, resulting in the appearance of a spin resonance. These findings underline the analogy to the cuprate high-temperature superconductors [5,6].…”

“…However, the excitations be-come fully inelastic when entering the superconducting state, resulting in the appearance of a spin resonance. These findings underline the analogy to the cuprate high-temperature superconductors [5,6].We conducted a comprehensive investigation of the magnetic order and superconductivity in CeCo(In0.9925Cd0.0075)5. Neutron scattering, magnetotransport and heat capacity, i.e., microscopic and macroscopic, spin and charge sensitive studies have been combined on flux-grown single crystals of the same batch.…”

Two gaps make a high-temperature superconductor?

“…16 This resonance is proposed by some to be a truly collective magnetic mode that, much in the same way as phonons mediate superconductivity in the conventional BCS superconductors, might constitute the bosonic excitation mediating superconductivity in the HTSCs. The total measured intensity, however, amounts to only a small portion of what is expected based on the sum rule for the magnetic scattering from a spin 1/2 system; 8,16,24,42,68,69 this weakness of the magnetic response should be part of the considerations in the modelling of magnetic-resonance mediated high-T c superconductivity. Alternatively, its detection below T c might be a mere consequence of the onset of superconductivity and of the corresponding suppression of quasiparticle scattering.…”

“…2 (only some representative datapoints are shown, such as not to overload the figure; similar compilations were obtained also by a number of other authors). 5,9,13,16,42,43,52,57,60,70,74,75 The data for these HTSCs with comparable T max c ∼ 95 K fall on two universal curves: a straight line for the pseudogap energy E pg = 2∆ pg , and a parabola for the superconducting energy scale E sc ∼ 5k B T c . The two curves converge to the same x ∼ 0.27 critical point at the end of the superconducting dome, similar to the cartoon of Fig.…”

“…Rather, we want to identify the general phenomenological picture emerging from the whole body of available experimental data. 5,9,13,16,18,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56 In the following, we will consider some of the most direct probes of low-energy, electronic excitations and spectral gaps, such as angle-resolved photoemission (ARPES), scanning tunneling microscopy (STM), superconductor/insulator/normal-metal (SIN) and superconductor/insulator/superconductor (SIS) tunneling, Andreev reflection tunneling (AR), and Raman scattering (RS), as well as less conventional probes such as heat conductivity (HC) and inelastic neutron scattering (INS). The emphasis in this review will be on spectroscopic data because of their more direct interpretative significance; however, these will be checked against thermodynamic/transport data whenever possible.…”