Title: Origin of Enhanced Electromechanical Coupling in (Yb,Al)N Nitride Alloys Show Chinese title

Title: (Yb,Al)N氮化物合金中增强的机电耦合效应的起源

Abstract: Our experiments demonstrate that alloying the cubic-phase YbN into the wurtzite-phase AlN results in clear mechanical softening and enhanced electromechanical coupling of AlN. First-principle calculations reproduce experimental results well, and predict a maximum 270% increase in electromechanical coupling coefficient caused by (1) an enhanced piezoelectric response induced by the local strain of Yb ions and (2) a structural flexibility of the (Yb,Al)N alloy. Extensive calculations suggest that the substitutional neighbor Yb-Yb pairs in wurtzite AlN are energetically stable along $c$ axis, and avoid forming on the basal plane of wurtzite structure due to the repulsion between them, which explains that (Yb,Al)N films with high Yb concentrations are difficult to fabricate in our sputtering experiments. Moreover, the neighbor Yb-Yb pair interactions also promote structural flexibility of (Yb,Al)N, and are considered a cause for mechanical softening of (Yb,Al)N. Show Chinese abstract

Abstract: 我们的实验表明，将立方相的YbN合金化到纤锌矿相的AlN中会导致明显的机械软化和AlN的增强压电耦合。 第一性原理计算很好地再现了实验结果，并预测由于(Yb离子的局部应变引起的压电响应增强以及(Yb,Al)N合金的结构柔性，导致压电耦合系数最大增加270%。 大量计算表明，在纤锌矿AlN中，替代邻近的Yb-Yb对沿$c$轴在能量上是稳定的，并且由于它们之间的排斥作用，避免在纤锌矿结构的基面上形成，这解释了为什么在我们的溅射实验中难以制备高Yb浓度的(Yb,Al)N薄膜。 此外，邻近的Yb-Yb对相互作用也促进了(Yb,Al)N的结构柔性，并被认为是(Yb,Al)N机械软化的诱因。