Stability and magnetism of FeN high-pressure phases

We have studied the formation and stability of high-pressure iron mono-nitride phases, and in particular a new magnetic phase with a NiAs-type structure.

Structural, electronic and mechanical properties ofCrN: A first principles study

The structural stability, electronic, and mechanical properties of chromium nitride ( CrN ) have been investigated by first-principles calculations within the generalized gradient approximation (GGA). Six different crystal structures of CrN are considered, namely NaCl , CsCl , zinc blende, WC, wurtzite and NiAs . Among the considered structures, NiAs -type structure is energetically more stable than others. The electronic band structure and density of states calculations reveal that these materials exhibit metallic nature. The calculated elastic constants indicate these compounds are mechanically stable in all the considered sturctures. In addition, the related mechanical properties such as bulk modulus, Young's modulus, shear modulus and the Poisson's ratio are also computed.

Phase stability and elastic properties of (W0.5Al0.5)C phase with a novel NiAs-type structure

Using density-functional theory, we show that the NiAs-type is a more favorable structure for the (W0.5Al0.5)C phase than the experimentally proposed WC-type structure when we compare the thermodynamic, dynamic and elastic properties of the two types.

The Effect of Pressure on Electronic and Magnetic Properties of MnAs Crystal

The structural, electronic, and magnetic properties of MnAs crystal are studied. The WIEN2k code which uses a full-potential LAPW program based on density functional theory with GGA is used for the calculations. At first, the total energy of a MnAs crystal in different lattices is calculated and the corresponding - diagram is drawn for two different structures of MnAs. The effect of pressuring this crystal is determined. The calculations confirm that, MnAs has the NiAs-type structure at ambient pressure but transforms into the zinc-blend structure of a specific pressure value. Also, the electric field gradient (EFG) and hyperfine field (HFF) at the nuclear site of Mn and As are calculated. Finally, the effect of pressure on EFG and HFF is studied.

THERMOMAGNETIC PROPERTIES OF RARE-EARTH REPLACEMENT CRITICAL MAGNETIC MATERIALS FROM DFT CALCULATION: MnBi AND MnSb

MnBi has gained much attention as a replacement for critical rare earth magnetic material not only due to its strong magnetization and coercive power, but also because of its capability to retain magnetization at elevated temperatures while most other compounds decline. To investigate the origin of this temperature dependence, we have performed a series of first principles electronic structure calculations on the thermomagnetic properties of MnBi and compared it with MnSb , another ferromagnetic material with a strong magnetic energy product, same crystal structure at room temperature and similar Curie temperature. Three structural phases were considered in this study: NiAs -type ( B81 ), MnP -type ( B31 ) and a zincblende-type ( B3 ) structures. Calculated magnetizations demonstrated structural effects on temperature dependent magnetization. For the same NiAs -type structure, MnBi has a monotonic increase in magnetization with increasing temperature while MnSb decreases. In the other two structures, magnetization in MnBi and MnSb are much less sensitive to temperature. Results from this study suggest a structural design rule for the development of new MnBi related materials.