X.T. Wang

First-principles study on quaternary Heusler compounds ZrFeVZ (Z = Al, Ga, In) with large spin-flip gap

First-principles calculations were used to systematically investigate the structural, electronic and half-metallic properties of newly designed quaternary Heusler compounds ZrFeVZ (Z = Al, Ga, In). The calculated results show that these three compounds have an excellent half-metallicity in their ferrimagnetic ground state. ZrFeVZ (Z = Al, Ga, In) compounds exhibit the large spin-flip gaps of 0.348 eV, 0.428 eV and 0.323 eV at their equilibrium lattice constants, respectively. The total spin magnetic moment is 2 μB for all the three compounds, which is in agreement with the Mt = Zt − 18 rule. The half-metallic properties of these three compounds are quite robust to the hydrostatic and tetragonal strain, and can also be kept when the electron correlation (U) is considered. For the ZrFeVIn compound, the spin-flip band gap achieves the maximum value (0.57 eV) under a small strain. The calculated Curie temperatures based on the mean field approximation (MFA) method are 818.04 K, 826.66 K, and 751.70 K for the ZrFeVAl, ZrFeVGa, and ZrFeVIn compounds, respectively. We hope that our current work may trigger Heusler compounds containing 4d transition metal elements and with quite large spin-flip band gaps for application in future spintronics devices.

Half-metallicity of the bulk and (001) surface of NbFeCrAl and NbFeVGe Heusler compounds: a first-principles prediction

Using first-principles calculations based on density-functional theory, the structural, electronic and magnetic properties in the bulk and (001) surfaces of quaternary Heusler compounds NbFeCrAl and NbFeVGe are investigated. For the bulk, the two compounds exhibit half-metallicity with band gaps of 0.4xa0eV and 0.2 eV in the majority-spin direction at their equilibrium lattice constants. The total magnetic moments are 2 μB following the Slater–Pauling formula: Mt = 24 − Zt rule. The half-metallicity can be maintained in the range of 5.76–6.07 A and 5.96–6.10 A (lattice constant), and 0.971–1.035 and 0.962–1.033 (c/a) for NbFeCrAl and NbFeVGe compounds, respectively. The half-metallicity is destroyed on the Fe–Cr, Nb–Al, Fe–V, and Nb–Ge terminated (001) surfaces, and the spin-polarization ratio sharply decreases below 50% for NbFeCrAl and NbFeVGe compounds.

First-principles study on the half-metallic properties of the d0 quaternary Heusler compounds: KCaCBr and KCaCI

With ab initio calculations, we studied the structural, electronic, and magnetic properties of quaternary Heusler compounds KCaCX (X = Br and I) adopted stable and metastable phases. We found that the most stable structure is type-3 atomic arrangement configuration where K, Ca, C, and X atoms occupy (0, 0, 0), (0.5, 0.5, 0.5), (0.25, 0.25, 0.25) and (0.75, 0.75, 0.75) positions, respectively. The metastable one is type-1 configuration where K, C, Ca and X occupy (0, 0, 0), (0.5, 0.5, 0.5), (0.25, 0.25, 0.25) and (0.75, 0.75, 0.75) positions, respectively. The results show that they are half-metallic ferromagnets with integer magnetic moments of 2.0 μB at their equilibrium lattice constants. It is also found that the spin-polarization is mainly from the C-2p states. In addition, KCaCBr compound with type-1 configuration shows an electronic transition from ordinary half-metallic state to zero-gap half-metallic state with the changing the lattice parameter.