Effect of Fe substitution on the electronic structure, magnetic and thermoelectric properties of Co2FeSi full Heusler alloy: A first principle study

• Full Potential Linear Augmented Plane Wave (FP-LAPW) calculations have done for Co2−xFe1+xSi (x = 0–1).
• The magnetic moment calculated using LDA+U approximation shows better comparison with experiment.
• Calculated negative Seebeck coefficient in a wide range temperature (0–800 K) agrees well with experimental values.
• From the calculated figure of merit, Fe2CoSi shows better thermoelectric behavior than Co2FeSi.

A large number of Heusler compounds have been discovered and their properties have been investigated both theoretically and experimentally. Among all the discovered Heusler compounds, Co2FeSi is focused for spintronic applications due to its high magnetic moment and high Curie temperature. In this aspect, the electronic structure, magnetic and thermoelectric properties of full Heusler alloy Co2−xFe1+xSi (x = 0–1) have been investigated by using first principle, Full Potential Linear Augmented Plane Wave method. The density of states calculation shows half-metallicity at x = 0 and 0.25 (i.e. Co2FeSi and Co1.75Fe1.25Si). The calculated magnetic moments were compared with experimental values measured at 4 K and also with the magnetic moments calculated by Slater–Pauling rule. The thermoelectric properties of Co2FeSi and Fe2CoSi were also calculated over a wide range of temperatures and it was found that Fe2CoSi shows higher figure of merit than Co2FeSi.

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