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In the present work, theoretical investigations of structural, electronic, magnetic, and thermoelectric properties of Cd 0.875 TM 0.125 O (TM = Mn, Fe, Co, Ni) half-metallic ferromagnets are done using WIEN2K code. The computed results when compared with the reported theoretical works reveal consistency. The band structures for spin up (↑), and spin down (↓) channels reveal the half metallic (Mn, Co, Fe), and frustrated (Ni) magnetism. The nature of magnetism has been analyzed in terms of hybridization among 3d states of TMs, individual Cd (5s, 4d) states, and O (2p) states. The control and function of the electron spin are revealed by calculating exchange energies (Δ x (d), Δ x (pd)), crystal field energy (ΔE cryst) and exchange constant (N o α, N o β), those play a very crucial role in understanding the magnetic nature. Moreover, double exchange and RKKY models are discussed to justify the observed half-metallic, and metallic behaviors, which are responsible for the magnetic moments to stabilize a magnetic polarization. The influence of electron spin is explained using the computed electrical and thermal conductivities, while thermoelectric power is elaborated by computing Seebeck coefficient and power factor. • Above room temperature ferromagnetism, and spintronic applications •Quantum spin of electrons dominant the charge with multifuctional properties •Exchange mechanism certifies the ferromagnetism by electron spin instead of magnetic ion clustering •Half metallic ferromagnetism and 100% spin polarization •Large value of electrical conductivity and ultralow low values of thermal conductivity. [ABSTRACT FROM AUTHOR]

Electron spin polarization properties of the Datta-Das spin field effect transistors are studied by taking into account the coexistence of the Rashba and Dresselhaus effects and an in-plane magnetic field. The transistor is connected to ferromagnetic leads with unparallel polarization. Transmission coefficients can be calculated and thus the Landauer-Büttiker conductance are obtained. Numerical results for the spin polarization of the conductance were discussed in detail. [ABSTRACT FROM AUTHOR]

The simultaneous existence of magnetic order and semiconducting nature in ferromagnetic semiconductors fascinate the spintronics technology to enhance the quantum computing and spin transistors. Therefore, electrons spin dependent ferromagnetism and thermoelectric properties of MgCr 2 X 4 (X ​= ​S, Se) spinels are scrutinized by density functional theory (DFT) based Wien2k code. The negative formation energy ensures thermodynamic stability. The band structures (BS) and density of states (DOS) ensure the ferromagnetic semiconductors nature of the studied spinel's. The insulating behavior in down spin and magnetic moment (Integer value) is the response of 100% spin polarization. The fulfillment of the condition Δ (d) > (Δ C F) and negative Δ (p d) have showed the dominant role of electrons spin to induce ferromagnetism. Moreover, influence of electrons spin on thermodynamic and thermoelectric characteristics are explored by specific heat capacity (C v), electrical conductivity (σ/τ), thermal conductivity ((κ/τ)), Seebeck coefficient (S) and power factor (σS2) by classical Boltzmann transport theory. The Ferromagnetic Semiconducting behavior of MgCr 2 X 4 (X ​= ​S, Se) in which up spin channel is semiconducting and down spin channel is insulating. Image 1 • The MgCr 2 X 4 (X ​= ​S, Se) spinels are ferromagnetic semiconductors with 100% spin polarization. • The exchange energies are exactly according to double exchange mechanism. • The above room temperature ferromagnetism enhance the potential for spintronics. • The thermal conductivity and electrical conductivity ratio is of the order of 10−5. [ABSTRACT FROM AUTHOR]