| Autor: |
Opeil, C. P., Mihaila, B., Schulze, R. K., Manosa, L., Planes, A., Hults, W. L., Fisher, R. A., Riseborough, P. S., Littlewood, P. B., Smith, J. L., Lashley, J. C. |
| Rok vydání: |
2008 |
| Předmět: |
|
| Zdroj: |
Phys. Rev. Lett. 100, 165703 (2008) |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1103/PhysRevLett.100.165703 |
| Popis: |
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 $100K < T < 250K$. All measurements detect clear signatures of the premartensitic transition ($T_\mathrm{PM}\sim 247K$) and the martensitic transition ($T_\mathrm{M} \sim 196K$). Temperature-dependent UPS shows a dramatic depletion of states (pseudogap) at $T_\mathrm{PM}$ located 0.3eV below the Fermi energy. First-principles electronic structure calculations show that the peak observed at 0.3eV in the UPS spectra for $T > T_\mathrm{PM}$ is due to the Ni-d minority-spin electrons. Below $T_\mathrm{M}$ this peak disappears, resulting in an enhanced density of states at energies around 0.8eV. This enhancement reflects Ni-d and Mn-d electronic contributions to the majority-spin density of states and is accompanied by significant reconstruction of the Fermi surface. |
| Databáze: |
arXiv |
| Externí odkaz: |
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