High Spin Polarization and Thermoelectric Efficiency of Half-Metallic Ferromagnetic CrYSn (Y=Ca, Sr) of Half-Heusler Compounds

Abstract

<jats:p> In the present work we have performed self-consistent ab-initio calculation using the full-potential linearized augmented plane-wave method (FP-LAPW), based on the density functional theory (DFT) as implemented in the Wien2k code to study the structural, electronic, magnetic, thermodynamic and thermoelectric properties of the half-heusler compound CrYSn ([Formula: see text], Sr) using generalized gradient approximation (GGA) described by Perdew–Burke–Ernzerhof (PBE), GGA+U and the modified Beck–Johnson correction (mBJ), the obtained results show that the compound is stable in the ferromagnetic state (FM) in [Formula: see text] phase on one hand and has a half-metallic character (metallic nature in spin up channel and semiconductor one in spin down channel with an indirect gap) on the other hand thus, the compound is a good candidate for spintronic applications, moreover it shows a very interesting thermoelectric predisposition in the minority spin or spin down channel at room temperature consisting of a very high Seebeck coefficient, high electrical conductivity and figure of merit near unity for the two compounds. The thermodynamic properties of CrCaSn and CrSrSn compounds using Gibbs code are studied for the first time. This study showed that these compounds can be used in extreme thermodynamic conditions. Since no experimental data were reported until now concerning this compound, our theoretical predictions of electronic, thermodynamic and thermoelectric properties are likely to be experimentally verified. </jats:p>

A new semiconducting full Heusler Li2BeX (X = Si, Ge and Sn): first-principles phonon and Boltzmann calculations

“…Discovery of Heusler alloys [1], has much interests that are paid due to very interesting properties and suitability for all kinds of potential applications [2] i.e. they have a conductive nature for the first one spin channel and semiconducting for the second spin channel leading to a possible use in the fields of spintronics [3,4], optoelectronics [5] and by existence of various intrinsic phenomena of magnetism to be utilized in magnetoelectronic devices like magnetic sensors and tunneling magneto-resistance (TMR), other hand, Heusler alloys have aroused a great interest as attractive candidate for future efficient thermoelectric (TE) materials [6][7][8] which will have an essential role in the realization of environment friendly technologies due to conversion of heat lost in electrical energy and reduced greenhouse gas emissions. The TE materials can be utilized into refrigeration devices for cooling applications as well as power generation devices.…”

Hubbard's parameter influence on Ba2GdReO6 properties, a promising ferromagnetic double Pérovskite oxide for thermoelectric applications

“…In order to describe the thermoelectric behavior of our double perovskite material Ba 2 GdReO 6 , it would be useful to know how a series of fundamental parameters evolve as a function of temperature (or chemical potential) such as electrical conductivity per relaxation time σ/τ , the Seebeck (or thermopower) coefficient S, the electronic thermal conductivity per relaxation time ke/τ and the figure of merit ZT. The variations of these four parameters mentioned previously as a function of the temperature for the double perovskite material Ba 2 GdReO 6 and according to different approximations, However, good materials suitable for thermoelectric applications must have a high Seebeck coefficient, a high electrical conductivity, a low thermal conductivity and a figure of merit close to unity or greater than unity [50][51][52][53], The transport properties of the compound Ba 2 GdReO 6 were determined using the BoltzTrap code [54] within the Wien2k program, and the approximation for the relaxation time constant τ as implemented in the BoltzTraP code is taken as 0.8 × 10 −14 s, as suggested in the BoltzTraP user manual, all these thermoelectric parameters as indicated above are calculated and analysed in the spin down state, and where our material is semi-conductive in nature with gap values of 2 eV, 2.18 eV and 3.03 eV for the approximations: mBJ-GGA, GGA+U (U = 2 eV) and GGA+U(U = 6 eV) respectively. The Seebeck effect is a phenomenon which consists of the appearance of a potential difference at the junction of two materials subjected to a difference (or a gradient) in temperature, this potential difference being generated by the movements of electrons free from the high temperature region to the low temperature region, in materials where the prevailing charge carriers are holes (p-type), the Seebeck coefficient has a positive sign, while those dominated by electrons (ntype) have negative Seebeck coefficients.…”

Exploring the Physical and Optoelectronic Properties of Co 2 ZrZ Compounds: Insights from Computational Analysis and Thermoelectric Characterization

“…Intelligently combining U and J into a single effective parameter U eff = U -J, we gain a comprehensive understanding of their interplay. It is important to note that the process of determining U eff involves the skilful application of the constraint LSDA method, pioneered by Anisimov et al, and extensively used in various scienti c works [33,34]. This sophisticated method allows us to unravel the electronic structure and intricate interactions within the system, offering valuable insights into the behaviour and properties of the Cobalt and Zirconium atoms within the Co 2 ZrZ compounds.…”