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Combined Experimental and Theoretical Investigation of the Premartensitic Transition in Ni2 MnGa Opeil, C. P. Mihaila, B. Schulze, R. K. Mañosa, Lluís Planes Vila, Antoni Hults, W. L. Fisher, R. A. Riseborough, P. S. Littlewood, P. B. Smith, J. L. Lashley, J. C. Física de partícules Experiments Particle physics Experiments Ultraviolet-photoemission (UPS) measurements and supporting specific-heat, thermal-expansion, resistivity, and magnetic-moment measurements are reported for the magnetic shape-memory alloy Ni 2 MnGa over the temperature range 100 < T < 250     K . All measurements detect clear signatures of the premartensitic transition ( T PM ∼ 247     K ) and the martensitic transition ( T M ∼ 196     K ). Temperature-dependent UPS shows a dramatic depletion of states (pseudogap) at T PM located 0.3 eV below the Fermi energy. First-principles electronic structure calculations show that the peak observed at 0.3 eV in the UPS spectra for T > T PM is due to the Ni d minority-spin electrons. Below T M this peak disappears, resulting in an enhanced density of states at energies around 0.8 eV. This enhancement reflects Ni d and Mn d electronic contributions to the majority-spin density of states. 2019-06-27T13:07:20Z 2019-06-27T13:07:20Z 2008-04-23 2019-06-27T13:07:20Z info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Reproducció del document publicat a: https://doi.org/10.1103/PhysRevLett.100.165703 Physical Review Letters, 2008, vol. 100, num. 16, p. 165703 https://doi.org/10.1103/PhysRevLett.100.165703 (c) American Physical Society, 2008 info:eu-repo/semantics/openAccess American Physical Society Articles publicats en revistes (Física de la Matèria Condensada)