Theoretical Investigations of the Electronic, Magnetic, and Thermoelectric Properties of Quaternary Heusler Alloys

Student: Hind Alqurashi

Degree: Ph.D., May 2023

Major Professor: Dr. Bothina Manasreh

Research Area(s):

Microelectronics

Modeling & Simulation

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Background/Relevance

  • Thermoelectric (TE) materials are solid state devices that could be designed using two dissimilar materials such as n type and p type semiconductors. They are designed to convert thermal energy from a temperature gradient into electrical energy and visa versa.

  • Quaternary Heusler alloys have received a great deal of attention due to their novel electronic structure, magnetic, and thermoelectric materials nature.

Innovation

  • Using Quaternary Heusler Alloys in thermoelectric and spintronic applications.

Approach

  • Calculations using density functional theory (were performed to investigate the structural, dynamical, electronic, magnetic, and thermoelectric properties of VTiRhZ (Z = Al, Ga, In, Si, Ge, Sn) alloys.
  • The semi-classical Boltzmann transport theory is used to calculate the thermoelectric properties that include seebeck coefficient, electrical conductivity, and electronic thermal conductivity of the materials.

    Key Results

    • Electronic, magnetic and thermoelectric properties of VTiRhZ (Z = Al, Ga, In, Si, Ge, Sn) alloys are investigated.
    • The total magnetic moment of VTiRhZ (Z= Al,Ga,In ) was found to be 3μB, and for VTiRhZ (Z=Si, Ge, Sn) exhibit integer values of 2μB.
    • The value of the power factor per relaxation time ranges between 7.2 × 10^11 Wm^-1 K^2 s^-1 and 14 × 10^11 Wm^-1 K^-2 s^-1.

    Conclusions

    • The band gap obtained using GGA-PBE approximation is slightly smaller than that obtained by GGA-mBJ . The calculations using GGA-mBJ functional are considered to give more reliable predictions for the band structure.

    • Quaternary Heusler Alloys can find significant applications as thermoelectric and spintronic materials.

    Future Work

    • Calculating lattice thermal conductivity.

    • Calculating figure of merit.