Dynamical instability and Fermi surface topology in Ni 2 FeGa from first principles
Dynamical instability and Fermi surface topology in Ni 2 FeGa from first principles
复制标题
从第一原理看 Ni 2 FeGa 的动力学不稳定性和费米表面拓扑
DOI：
10.1103/physrevb.89.085114
复制
发表时间：
2014
影响因子：
3.7
通讯作者：
M. B. Sahariah
中科院分区：
文献类型：
--
作者：
Satyananda Chabungbam;S Gowtham;M. B. Sahariah
采用第一性原理密度泛函微扰理论计算了化学计量比Heusler合金${\text{Ni}}{2}$FeGa高温立方奥氏体相的声子谱。我们还从声学声子分支的初始斜率计算了合金的弹性常数。沿[110]方向的${\text{TA}}_{2}$声子分支沿着方向出现软化，在$\ensuremath{\zeta}=0.58$处出现最小倾角，表明马氏体相变前可能存在调制相。我们还映射了这种合金的费米表面在3D和2D检查任何嵌套矢量的存在。观察到的嵌套参数与上述[110]方向上声子软化发生的波矢值吻合得很好。
The phonon spectrum of stoichiometric Heusler alloy ${\text{Ni}}_{2}$FeGa is calculated for the high-temperature cubic austenite phase by using first-principles density functional perturbation theory. We also compute the elastic constants of the alloy from the initial slopes of the acoustic phonon branch. The ${\text{TA}}_{2}$ phonon branch along [110] direction shows softening with a minimum dip at $\ensuremath{\zeta}=0.58$ which indicates the possibility of modulated phases prior to martensitic transformation. We also map the Fermi surface of this alloy both in 3D and 2D to check the presence of any nesting vectors. The observed nesting parameter is in good agreement with the above value of the wave vector in the [110] direction where phonon softening occurs.