Electronic, Magnetic And Fermi Surface Properties Of Cu2MnX ( X=Al, In, Sn): Ab-Initio Study

Chawla, Mukesh and V, Kanchana (2013) Electronic, Magnetic And Fermi Surface Properties Of Cu2MnX ( X=Al, In, Sn): Ab-Initio Study. Masters thesis, Indian Institute of Technology Hyderabad.

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Abstract

The band structure, density of states, Fermi surface (FS) topology and vibrational properties of the ferromagnetic Heusler alloys, Cu2MnX (X = Al, In, Sn) have been studied using the first principles electronic structure calculation at ambient as well as under compression. The major contribution to the total magnetic moment arises from the Mn atom with adequate exchange splitting as revealed from the calculated local magnetic moment as well as from the density of states plots. The Fermi surface topology is found to be similar for the majority band for all the compounds and remain unaltered under compression, where we have seen the linear variation of the density of states (N(EF)) at the Fermi level, whereas the FS topology change is observed in the minority spin band with non-monotonic variation of the N(EF). Apart from this, under compression at nearly V/V0=0.75, we have seen the Fermi surface topology of the minority spin of Cu2MnSn to change drastically resembling the majority band Fermi surface. From the phonon dispersion relation, we find a lattice instability in the case of Cu2MnSn with negative slope around Γ point at ambient as well as under compression and this might induce the anomalous behavior observed in the Fermi surface topology, whereas for other compounds we have found the positive slope at the same point with all positive frequency under all compression, ensuring the dynamical stability of these compounds. Contents

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