Vanishing Fe 3d orbital moments in single-crystalline mag- netite

– We show detailed magnetic absorption spectroscopy results of an in situ cleaved high quality single crystal of magnetite. In addition the experimental setup was carefully optimized to reduce drift, self absorption, and offset phenomena as far as possible. In strong contradiction to recently published data, our observed orbital moments are nearly vanishing and the spin moments are quite close to the integer values proposed by theory. This very important issue supports the half metallic full spin polarized picture of magnetite. Introduction. – Magnetite Fe3O4 has been fascinating mankind for thousands of years [1]. Fe3O4 shows a phase transition, the so called Verwey transition at TV ≈ 123K, accompanied with a jump in the electrical conductivity, which has been extensively investigated in the last century (For a review see Ref. [2] or [3] and references therein). Today magnetite has attracted enormous interest, because of the proposed high-spin-polarization and related possible applications for future spin-electronic-devices [4]. The nature of the conducting electrons and the influence of local electronic correlations are one of the key issues to understand Fe3O4 [5]. Fe3O4 crystallizes at room temperature in the antiferromagnetic cubic inverse Spinel structure (Fd3m), formally written as Fe(A)Fe(B)2O4 [6]. The A-type ions are tetrahedrally coordinated and nominally in a Fe (≈ -5μB) configuration. The B-site ions are located on octahedral sites and mixed valent with equally distributed Fe (≈ +5μB) and Fe (≈ +4μB) ions. The magnetic moments shown in brackets are pure spin moments related to a fully occupied local majority band (opposite for A and B sites). The magnetic moments of the A and B sites are aligned antiparallel to each other with a resulting magnetization per formula unit 5μB(B)+4μB(B)-5μB(A)= 4μB, consistent to the experimental result of 4.07μB [7]. An observation of an integer spin moment is therefore a clear indication for a B-site minority electron conduction mechanism, and its accompanied full spin polarization at the Fermi level. The phase transition at TV = 123K been has explained by Verwey in terms of a charge localization-delocalization of the conducting B-site electrons [8–10]. This discussion is recently revived experimentally and theoretically by refined structural data results [11–13], which found only a slightly corrugated charge order between 2.4-2.6e, accompanied by orbital