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The electronic structure of 4f local moment systems

Takashi Komesu, University of Nebraska - Lincoln

Abstract

Local moment systems, especially the 4f-electron systems, are archetypal candidate materials to investigate the influence of band structure on several magnetic properties of (anti-) ferromagnetism. These magnetic materials are dominated by the strong exchange coupling between the relatively large 4f local moments, mediated by the valence and conduction electrons near the Fermi level (EF), and are model of RKKY type systems. These materials exhibit strong wave vector dependent exchange splitting: the energy difference between majority (spin up) and minority (spin down) bands. The electronic structures in these systems show the significant influence of symmetry and orbital overlap in the band structure. This can be probed with spin-polarized photoemission (SPES) and spin-polarized inverse photoemission (SPIPES). ^ The rare-earth, Gadolinium (Gd) and the rare earth pnictide compound, Erbium Arsenide (ErAs), have been a subject of much discussion regarding band structure because of the “coupled” magnetic and electronic properties. Gadolinium is the great candidate for investigating the electronic structure of a local moment 4f magnet. Gd thin films grown on Mo(112) surface have been studied for a long time because of the strained hcp (4% expansively strained with thickness more than 50 Å). Expansive strain enhances the gadolinium magnetism reflected in the electronic structure. In addition, I have found indications of d-f hybridization, in strained Gd(0001). ^ The experimental band structure of ErAs, grown epitaxially on GaAs(100), has been mapped out using photoelectron spectroscopy (PES) and inverse photoemission spectroscopy (IPES). The electronic structure is dominated by bulk bands qualitatively consistent with the calculated band structure, though a number of additional nondispersing multiplet levels can be identified in the valence band structure, as well as at least one surface resonance band. From symmetry selection rules, photoemission provides strong evidence that the Δ5 (or e) symmetry bands are a consequence of hybridization between Er and As, while the Δ1 (or a1) symmetry bands have possible contributions from nonbonding or antibonding states from Er (and/or As). Again, I find indications of 5d-4f hybridization. ^

Subject Area

Physics, Electricity and Magnetism|Physics, Condensed Matter

Recommended Citation

Komesu, Takashi, "The electronic structure of 4f local moment systems" (2002). ETD collection for University of Nebraska - Lincoln. AAI3070131.
http://digitalcommons.unl.edu/dissertations/AAI3070131

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