First-principles investigations of the half-metallic ferromagnetic LaCoTiIn equiatomic quaternary Heusler alloy for spintronics

We have evaluated the structural and mechanical stability, electronic structure, total spin magnetic moment, and Curie temperature of LaCoTiIn Equiatomic Quaternary Heusler Alloy (EQHA) using first-principles studies. The Generalized Gradient Approximation (GGA) and GGA+U schemes have been used as exchange-correlation functional for the above calculations. From the ground state calculation, LaCoTiIn EQHA with a Type-III structure in the ferromagnetic (FM) state is found to be stable. The electronic structure of LaCoTiIn EQHA depicts half-metallic behavior which has metallic overlap in the spin up ([Formula: see text] channel and a semiconductor band gap in the other channel. The spin–orbit coupling of LaCoTiIn has a great influence on the band gap of the material. The computed band gap values for the spin down ([Formula: see text] channel are 0.480 eV and 0.606 eV by using the GGA and GGA+U schemes. The total spin magnetic moment is 1 [Formula: see text], according to the Slater–Pauling rule, [Formula: see text] = ([Formula: see text] - 18) [Formula: see text]. These results obtained can be used as a valuable reference for future research, or they will be used to further motivate the experimental synthesis of the corresponding alloy.

Quantum chemical insight into the effects of the local electron environment on T2*-based MRI

T2* relaxation is an intrinsic magnetic resonance imaging (MRI) parameter that is sensitive to local magnetic field inhomogeneities created by the deposition of endogenous paramagnetic material (e.g. iron). Recent studies suggest that T2* mapping is sensitive to iron oxidation state. In this study, we evaluate the spin state-dependence of T2* relaxation using T2* mapping. We experimentally tested this physical principle using a series of phantom experiments showing that T2* relaxation times are directly proportional to the spin magnetic moment of different transition metals along with their associated magnetic susceptibility. We previously showed that T2* relaxation time can detect the oxidation of Fe2+. In this paper, we demonstrate that T2* relaxation times are significantly longer for the diamagnetic, d10 metal Ga3+, compared to the paramagnetic, d5 metal Fe3+. We also show in a cell culture model that cells supplemented with Ga3+ (S = 0) have a significantly longer relaxation time compared to cells supplemented with Fe3+ (S = 5/2). These data support the hypothesis that dipole–dipole interactions between protons and electrons are driven by the strength of the electron spin magnetic moment in the surrounding environment giving rise to T2* relaxation.

Systematic investigation of magnetic, optical and transport properties of RTX (R = Rareearth, T = 3d/4d and X = p−block elements) for thermoelectric applications

The half-Heusler compounds have been extensively studied because of their exceptional transport properties. We have explored rare earth (RE)-based half-Heusler bismuthides compounds, [Formula: see text]PdBi ([Formula: see text][Formula: see text]=[Formula: see text]Gd, Dy and Ho) with the cubic crystal structure. Structural, magnetic, optical and transport properties are investigated using PBE-GG approximations by solving exchange-correlation potential. Electronic properties including spin-polarized band structure and density of states verified that semimetals with half-filled [Formula: see text]-orbitals across the Fermi-level are useful for thermoelectric applications. Magnetic properties reveal that values of the total spin magnetic moment are in close agreement with the experimental data. Optical properties with spin–orbit coupling (SOC) have a higher absorption coefficient and comparatively lesser energy loss which shows that studied materials are appropriate for optoelectronic devices. Moreover, transport properties including electrical and thermal conductivities, Seebeck coefficient, specific heat, power factor and figure of merit have been discussed in detail. The consistency of our results with the literature reveals that SOC plays a vital role in the transport properties of the materials.

Quark Self-Energy and Condensates in NJL Model with External Magnetic Field

In a one-flavor NJL model with a finite temperature, chemical potential, and external magnetic field, the self-energy of the quark propagator contains more condensates besides the vacuum condensate. We use Fierz identity to identify the self-energy and propose a self-consistent analysis to simplify it. It turns out that these condensates are related to the chiral separation effect and spin magnetic moment.

Bonding and Stability of Ternary Structures in the CeT2Al20 (T=Ta, W, Re) and YRe2Al20 Alloys

A-T-Al aluminides, where A = actinide, lanthanide or rare earth elements and T=transition metals, have attracted considerable attention as potential materials where heavy fermions may be formed. This led to the discovery of superconducting properties in cubic AT2Al20 compounds with CeCr2Al20-type crystal structure. Other Al-rich aluminides, belonging to these A-T-Al systems, exhibited different physical properties as a function of their crystal structure. Thus, predicting the stable structure of the Al-richest phase that will form in the A-T-Al systems is highly valuable. Stability of the crystal structures, forming in the CeT2Al20 and YRe2Al20 systems, was studied in current research using density functional theory (DFT) calculations. It is demonstrated that the total spin magnetic moment of the transition metal can be used as a descriptor for phase stability assessment in the AT2Al20 systems, where T is a 5d transition metal. Basing on crystallographic considerations, degree of distortion of the coordination polyhedrons, formed around T atoms, can be directly connected to the specific type of structure crystallizing in these systems.

Surface-orientation- and ligand-dependent quenching of the spin magnetic moment of Co porphyrins adsorbed on Cu substrates

The magnetism of adsorbed Co porphyrin molecules is controlled by their ligands and the substrate's orientation.