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arXiv 2304.04992cond-mat.mtrl-sci
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采用密度泛函理论与硬X射线光电子能谱研究Ni₂MnGa的体电子结构

Bulk Electronic Structure of Ni2MnGa studied by Density Functional Theory and Hard X-ray Photoelectron Spectroscopy

Joydipto Bhattacharya, Pampa Sadhukhan, Shuvam Sarkar, Vipin Kumar Singh, Andrei Gloskovskii, Sudipta Roy Barman, Aparna Chakrabarti

AI总结:

本研究结合DFT与硬X射线光电子能谱,证实单晶Ni₂MnGa马氏体相的调制结构为真实结构,且存在CDW态与赝能隙,明确原子调制对其CDW相的关键作用。

摘要:

本工作结合采用基于实验测定调制结构的密度泛函理论(DFT)与对体相敏感的硬X射线光电子能谱,对单晶Ni₂MnGa开展了联合研究。对于上述调制结构,实验价带(VB)中的所有特征峰均与DFT计算的理论价带高度吻合,表明该调制结构是马氏体相Ni₂MnGa的真实表征。我们根据费米能级(E_F)附近的价带形状,证实了马氏体相中存在电荷密度波(CDW)态,其谱权重转移与DFT计算结果高度一致。此外,通过用理论预测的CDW相幂律函数拟合E_F附近区域,证实了赝能隙的存在。因此,本工作强调,原子调制在体相化学计量比Ni₂MnGa的CDW相形成中发挥着重要作用。

英文摘要:

A combined study employing density functional theory (DFT) using the experimentally determined modulated structures and bulk-sensitive hard x-ray photoelectron spectroscopy on single-crystalline Ni$_2$MnGa is presented in this work. For the aforementioned modulated structures, all of the characteristic features in the experimental valence band (VB) are in excellent agreement with the theoretical VB calculated from DFT, evincing that it is the true representation of Ni$_2$MnGa in the martensite phase. We establish the existence of a charge density wave (CDW) state in the martensite phase from the shape of the VB near $E_F$ that shows a transfer of spectral weight in excellent agreement with DFT. Furthermore, presence of a pseudogap is established by fitting the near $E_F$ region with a power law function predicted theoretically for the CDW phase. Thus, the present work emphasizes that the atomic modulation plays an important role in hosting the CDW phase in bulk stoichiometric Ni$_2$MnGa.

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