Combined experimental and theoretical investigation of the premartensitic transition in Ni${}_2$MnGa

Abstract

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.

References in corpus (3)

• Observation of a strongly nested Fermi surface in the shape-memory alloy Ni[0.62]Al[0.38]
• Angle-resolved photoemission and first-principles electronic structure of single-crystalline $\alpha$-uranium (001)
• Electronic Instabilities in Shape-Memory Alloys

Cited by in corpus (13)

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• Temperature dependence of the anomalous Nernst effect in Ni${}_2$MnGa shape memory alloy
• Structural and Magnetic Dynamics in the Magnetic Shape Memory Alloy Ni${}_2$MnGa
• Electronic structure beyond the generalized gradient approximation for Ni${}_2$MnGa
• Coherent phonon dynamics at the martensitic phase transition of Ni_2MnGa
• Observation of atomically displacive transformation out of the boundary-reconstructive phase competition
• Observation of inverse magnetocaloric effect in magnetic-field-induced austenite phase of Heusler Alloys Ni50-xCoxMn31.5Ga18.5 (x = 9 and 9.7)
• Driving force for martensitic transformation in Ni${}_2$Mn${}_{1+x}$Sn${}_{1-x}$
• Injective and non-injective realizations with symmetry
• Magnetic phase diagram of the austenitic Mn-rich Ni-Mn-(In,Sn) Heusler alloys
• Stress-induced Martensitic transformation in epitaxial Ni-Mn-Ga thin films and its correlation to optical and magneto-optical properties