ARPES SPECTRAL FUNCTIONS AND FERMI SURFACE FOR La_1.86 Sr_0.14 CuO₄ COMPARED WITH LDA+DMFT+Σ_k CALCULATIONS
Nekrasov I.A., Kokorina E.E., Kuchinskii E.Z., Sadovskii M.V., Kasai S., Sekiyama A., Suga S.

Received: November 6, 2009

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The slightly underdoped high-temperature system La_1.86 Sr_0.14 CuO₄ (LSCO) is studied by means of high-energy high-resolution angular resolved photoemission spectroscopy (ARPES) and the combined LDA+DMFT+Σ _k computational scheme. The corresponding one-band Hubbard model is solved via dynamical mean field theory (DMFT), and the model parameters needed are obtained from first principles in the local density approximation (LDA). An ``external'' k-dependent self-energy Σ<sub>\textbf{k}</sub> describes the interaction of correlated electrons with antiferromagnetic (AFM) pseudogap fluctuations. Experimental and theoretical data clearly show the ``destruction'' of the LSCO Fermi surface in the vicinity of the (π,0) point and formation of ``Fermi arcs'' in the nodal directions. ARPES energy distribution curves as well as momentum distribution curves demonstrate a deviation of the quasiparticle band from the Fermi level around the (π,0) point. The same behavior of spectral functions follows from theoretical calculations suggesting the AFM origin of the pseudogap state.