Probing of Ferromagnetism and Electronic transport characteristics of Rare‐earth‐based CdEr2X4 (X = S, Se) Spinels for Spintronic and Energy Harvesting Applications

Highlights: • Density functional theory studies were carried out to probe the physical properties of chalcogens having compositions CdEr₂X₄ (X = S, Se) in variety of spintronic and energy harvesting devices. • The calculated results recognized the stability of ferromagnetic (FM) state and the same was demonstrated by enthalpy of formation. For investigated compounds, the verification of elastic stability conditions justifies their possible use in mechanical device applications. • Ferromagnetic behavior is further verified by the existence of higher ground state energy in FM states than that of NM states. The interpretation regarding strong exchange interactions and strong hybridizations confirmed the solo role of electronic spin to ferromagnetism in both chalcogens. • Magnetic semiconducting behavior of materials was attributed to integral multiple value of total magnetic moment equal to 5 μB. • Further investigations regarding mechanical behavior for device applications were done by computations of elastic properties. The promising role of our investigated compounds in the field of spintronics, spin injectors and energy harvesting is manifested because of their fair Seebeck coefficient and power factor, at ambient temperatures. • Moreover, many other theoretically calculated parameters in this research study confirms the futuristic role of the materials CdEr₂X₄ (X = S, Se) in variety of spintronic and energy harvesting devices. -- Abstract: In order to investigate the source of ferromagnetic semiconducting behavior of the materials, CdEr₂X₄ (X = S, Se), full potential methods have been employed for their elastic, structural, transport and electronic characterizations. The measured values of enthalpy of formation have been effectively used to explain ferromagnetic (FM) state stability. The ductile behavior of investigated materials has been revealed from the calculated values of elastic constants and their corresponding mechanical modules. Rather than PBEsol-GGA, we have employed mBJ potentials that in turn produced more accurate and precise results revealing complete band occupation in the materials as well as clear interpretation of DOS (density of states) is achieved. The probing of electronic band structure and density of states led to the result that FM state's stability in the investigated materials is due to p-d hybridization-based exchange splitting of Erbium (Er) cations present in the lattice. The sharing of charge, spin and magnetic moment between host anions and impurity cations clearly indicate the exchange splitting of bands. The thermoelectric coefficients calculations are helpful to check the potential applicability of material in recovery systems of waste energy as well as various technological uses. Thermal parameters own vital importance to check the thermal stability of material over a wide span of temperatures. Thermoelectric appliances and spintronics based devices are highly dependent upon thermoelectric parameters.