The electronic band structure of a prototype ${\text{Ni}}_2\text{MnGa}$ magnetic shape-memory alloy was studied in the weakly off-stoichiometric regime, using ${\text{Ni}}_{49.7}{\text{Mn}}_{29.1}{\text{Ga}}_{21.2}$ single-crystal samples. In the austenitic phase, isoenergetic $k$-space cuts through the entire Brillouin zone were measured by momentum-resolved photoelectron microscopy in the energy range $(E_{\mathrm{F}}-3\mathrm{eV},E_{\mathrm{F}})$, where $E_{\mathrm{F}}$ is the Fermi energy. The results are compared to simulations based on the ab initio density functional theory. Two regions were identified in the band structure. In the first one, between $E_{\mathrm{F}}-1\mathrm{eV}$ and $E_{\mathrm{F}}$, the minority spin $d\text{electrons}$ of Ni dominate the density of states showing a significant dispersion as a function of the $k$ vector. The second one, between $E_{\mathrm{F}}-3\mathrm{eV}$ and $E_{\mathrm{F}}-1\mathrm{eV}$, is controlled by majority-spin Mn $d\text{electrons}$. The dispersion is perturbed by a relatively high degree of disorder, producing an image of electronic states in the form of a spectral density of states.

• Received 12 August 2014
• Revised 19 February 2015

DOI:https://doi.org/10.1103/PhysRevB.91.165115