Critical Test for Altshuler-Aronov Theory: Evolution of the Density of States Singularity in Double PerovskiteSr2FeMoO6with Controlled Disorder

Abstract

With high-resolution photoemission spectroscopy measurements, the density of states (DOS) near the Fermi level (EF) of double perovskite Sr2FeMoO6 having different degrees of Fe/Mo antisite disorder has been investigated with varying temperature. The DOS near EF showed a systematic depletion with increasing degree of disorder, and recovered with increasing temperature. AltshulerAronov (AA) theory of disordered metals well explains the dependences of the experimental results. Scaling analysis of the spectra provides experimental indication for the functional form of the AA DOS singularity.PACS numbers: 71.20.-b, 71.23.-k, 71.27.+a, 79.60.-i Disordered electronic systems, which have random potentials deviating from an ideal crystal, have been investigated from both fundamental and application points of view [1]. Ever since the finding of filling-control metalinsulator transitions (MIT) in transition-metal oxides known as strongly correlated system, disorder has attracted even more attention because not only electronelectron interaction but also disorder are supposed to play fundamentally important roles in the MIT. Altshuler and Aronov [2] studied the effect of electron-electron interaction in a disordered metallic medium, and predicted that the density of states (DOS) near the Fermi level (E F ) shows a singularity of |E − E F | 1/2 and the DOS at E F increases with increasing temperature in proportion to √ T . The theory has been applied to the low temperature conductivity of disordered metals such as disordered Au and Ag films [3], amorphous alloy Ge 1−x Au x [4], and transition metal chalcogenide Ni(S,Se) 2 [5].In a previous work, Sarma et al. [6] have reported photoemission (PES) measurements on B-site disordered perovskites LaNi 1−x M x O 3 (M =Mn and Fe), which show MIT as a function of x, and shown that the disorder affects the DOS near E F in such a way that had been theoretically predicted by Altshuler and Aronov [2]. In a similar B-site substituted transition-metal oxide SrRu 1−x Ti x O 3 , which demonstrates MIT at x ∼ 0.3 (SrRuO 3 is metallic), the depletion of the DOS near E F has shown an unusual |E − E F | 1.2 dependence in both metallic and insulating phases [7]. In addition, although it is believed that a disorder-induced insulator shows a soft Coulomb gap characterized by a (E − E F ) 2 dependence of the DOS near E F [8, 9], the unexpected |E − E F | 3/2 dependence of the DOS near E F related to charge density wave has been observed in insulating BaIrO 3 [10]. It is considered that fine structure in the DOS in the vicinity of E F is sensitive to both the degrees of disorder and electron correlation, and therefore experimental confirmation of a basic theory for disordered electronic system such as the Altshuler-Aronov (AA) theory is necessary for understanding of the DOS singularity. While AA theory makes specific predictions about both E and T dependences, photoelectron spectroscopy has been used only to probe the E dependence with absolutely no reference to the T dependence. Therefore, detai...

Complex spectral evolution in a BCS superconductor, ZrB12

“…The decrease in intensity at with the decrease in temperature may arise due to the disorder induced localization of the electronic states. Altshuler & Aronov showed that the charge disorder in a correlated system leads to dependence of the density of states near Fermi level20, which has been proved employing photoemission spectroscopy2122. In the present case, a plot of SDOS with shown in Fig.…”

Multiband One-Dimensional Electronic Structure and Spectroscopic Signature of Tomonaga-Luttinger Liquid Behavior in K2Cr3AsWatson1, Feng2, Nicholson3 et al. 2017Phys. Rev. Lett.593410View full textAdd to dashboardCite

“…The Altshuler-Aronov theory for interacting disordered metals [19] predicts that density of states near the Fermi level is a nonzero constant plus an anomalous power law contribution (in 3D) [21]. However, we can dismiss this assignment since our measured DOS extrapolates to zero at the Fermi level even though the samples are good conductors.…”

“…097002-3 disorder and electron interactions may also deplete the DOS near the Fermi level [18,19], which has recently been proposed for the interpretation of ARPES spectra [20,21]. The Altshuler-Aronov theory for interacting disordered metals [19] predicts that density of states near the Fermi level is a nonzero constant plus an anomalous power law contribution (in 3D) [21].…”

Fermi level position, Coulomb gap and Dresselhaus splitting in (Ga,Mn)As

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