LDA+DMFT Spectral Functions and Effective Electron Mass Enhancement in Superconductor LaFePO
Abstract
In this Letter we report the first LDA+DMFT results (method combining Local Density Approximation with Dynamical Mean-Field Theory) for spectral properties of superconductor LaFePO. Calculated k-resolved spectral functions reproduce recent angle-resolved photoemission spectroscopy (ARPES) data [D. H. Lu et al., Nature 455, 81 (2008)]. Obtained effective electron mass enhancement values m*/m≈ 1.9 -- 2.2 are in good agreement with infrared and optical studies [M. M. Qazilbash et al., Nature Phys. 5, 647 (2009)], de Haas--van Alphen, electrical resistivity, and electronic specific heat measurements results, that unambiguously evidence for moderate correlations strength in LaFePO. Similar values of m*/m were found in the other Fe-based superconductors with substantially different superconducting transition temperatures. Thus, the dynamical correlation effects are essential in the Fe-based superconductors, but the strength of electronic correlations does not determine the value of superconducting transition temperature.