TY  - EJOU
AU  - Fida, M. 
AU  - Nasarullah, 
AU  - Aldaghfag, S. A. 
AU  - Yaseen, M. 
AU  - Ishfaq, M. 

TI  - Systematic investigation of magneto-electronic, structural, thermoelectric and optical properties of Nd<sub>2</sub>MgX<sub>4</sub> (X = S, Se) compounds
T2  - Chalcogenide Letters

PY  - 2023
VL  - 20
IS  - 8
SN  - 1584-8663

AB  - The structural, magnetic, optoelectronic, and thermoelectric (TE) characteristics of 
Nd<sub>2</sub>MgX<sub>4</sub> (X = S, Se) are determined by utilizing the density functional theory (DFT) 
based full potential linearized augmented plane wave (FP-LAPW) method as employed in 
WEIN2k code. The exchange and correlation energies along with Coulomb interactions 
are brought into consideration by employing local density of approximation with Hubbard 
model (LDA+U). Tolerance (τ) factor and formation enthalpy were utilized to confirm the 
stability of both spinels. τ values are 0.70 and 0.68, and formation enthalpy values are 
(ΔH<sub>f</sub>) are -3.34 eV and -2.19 eV for Nd<sub>2</sub>MgX<sub>4</sub> (X = S, Se), respectively. For Nd<sub>2</sub>MgX<sub>4</sub> (X 
= S, Se) metallic behavior is found in spin up case while considerable bandgaps are found 
in spin down with half metallic bandgap (E<sub>g</sub>) values of 1.82 and 1.26 eV (in spin down), 
correspondingly. The calculated magnetic moment for Nd<sub>2</sub>MgX<sub>4</sub> (X = S, Se) are 12.0008 
μ<sub>B</sub> and 12.0003 μ<sub>B</sub>, respectively. Furthermore, optical features including refractive index 
n(ω), dielectric constant ε(ω), reflectivity R(ω), optical conductivity σ(ω), absorption 
coefficient α(ω) and extinction coefficient k(ω) are computed. The maximum calculated 
real part of dielectric constant ε<sub>1</sub>(ω) values for Nd<sub>2</sub>MgX<sub>4</sub> (X = S, Se) are 9.2 and 10.8, 
respectively. For Nd<sub>2</sub>MgX<sub>4</sub> (X = S, Se), σ(ω) has maximum value of 7642.9 at 6.6 and 
7592.5 (Ω cm)
<sup>-1</sup>
 at 5.99 eV, respectively. The various temperature dependent 
thermoelectric (TE) parameters along with figure of merit (ZT) are determined to get full 
insight into the TE behavior for both compounds by using BoltzTraP code. The computed 
ZT value for Nd<sub>2</sub>MgSe<sub>4</sub> is 0.81 at 800 K while Nd<sub>2</sub>MgS<sub>4</sub> has ZT value of 0.80 at 800 K. 
Results showed that both spinels have potential in spintronics and in cooling industries.
KW  - Ferromagnetism
KW  -  DFT
KW  -  Spintronics
KW  -  Spinels

DO  - 10.15251/CL.2023.208.559