Doping driven small-to-large Fermi surface transition and d-wave superconductivity in a two-dimensional Kondo lattice
R. Eder, P. Wróbel
DOI 10.1103/PhysRevB.84.035118 · Physical Review B
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Abstract
We study the two-dimensional Kondo lattice model with an additional Heisenberg exchange between localized spins. In a first step, we use mean-field theory with two order parameters. The first order parameter is a complex pairing amplitude between conduction electrons and localized spins that describes condensation of Kondo (or Zhang-Rice) singlets. A nonvanishing value implies that the localized spins contribute to the Fermi surface volume. The second-order parameter describes singlet pairing between the localized spins and competes with the Kondo-pairing order parameter. Reduction of the carrier density in the conduction band reduces the energy gain due to the formation of the large Fermi surface and induces a phase transition to a state with strong singlet correlations between the localized spins and a Fermi surface that comprises only the conduction electrons. The model thus shows a doping driven change of its Fermi surface volume. At intermediate doping and low temperature, there is a phase where both order parameters coexist, which has a gapped large Fermi surface and dx2−y2 superconductivity. The theory thus qualitatively reproduces the phase diagram of cuprate superconductors. In the second part of this paper, we show how the two phases with different Fermi surface volume emerge in a strong-coupling theory applicable in the limit of large Kondo exchange. The large Fermi surface phase corresponds to a “vacuum” of localized Kondo singlets with uniform phase, and the quasiparticles are spin-1/2 charge fluctuations around this fully paired state. In the small Fermi surface phase, the quasiparticles correspond to propagating Kondo singlets or triplets whereby the phase of a given Kondo singlet corresponds to its momentum. In this picture, a phase transition occurs for low filling of the conduction band as well.
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| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Tl2Ba2CuO6+x Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| Sr2Cu2O2Cl2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| Ca2CuO2Cl2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| Bi2(Sr2-xLax)CuO6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| YBa2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| YBa2Cu3O6.5 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| YBa2Cu4O8 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| YBa2Cu3O6.6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| Bi2Sr2CaCu2O8+δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| YBa2Cu3O6+x Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| CeRu2Si2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| CeRh1-xCoxIn5 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| CeRh2Si2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| CeRhIn5 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| CeIn3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |