Band structure of Heusler compounds studied by photoemission and tunneling spectroscopy [Elektronische Ressource] / Elena Arbelo Jorge

Band structure ofHeusler Compounds studied byPhotoemission and TunnelingSpectroscopyDissertationzur Erlangung des GradesDOKTOR DER NATURWISSENSCHAFTENam Fachbereich 08der Johannes Gutenberg-Universit¨atin MainzElena Arbelo Jorgegeboren in Santa Ursula, Tenerife, SpainMainz, 2011“Scientific knowledge is a body ofstatements of varying degrees of certainty,some most uncertain, some nearly sure,none absolutely certain”(R. P. Feynman)AbstractHeusler compounds are key materials for spintronic applications. They have at-tracted a lot of interest due to their half-metallic properties predicted by bandstructure calculations.The aim of this work is to evaluate experimentally the validity of the predic-tions of half metallicity by band structure calculations for two specific Heuslercompounds, Co FeAl Si and Co MnGa. Two different spectroscopy methods2 0.3 0.7 2for the analysis of the electronic properties were used: Angular Resolved Ultra-violet Photoemission Spectroscopy (ARUPS) and Tunneling Spectroscopy.Heusler compounds are prepared as thin films by RF-sputtering in an ultrahigh vacuum system.For the characterization of the samples, bulk and surface crystallographic andmagnetic properties of Co FeAl Si and Co MnGa are studied. X-ray and elec-2 0.3 0.7 2tron diffraction reveal a bulk and surface crossover between two different typesof sublattice order (from B2 to L2 ) with increasing annealing temperature.