Hole distribution in (Tl0.5Pb0.5)Sr2(Ca1-xYx)Cu2O7 studied by x-ray absorption spectroscopy.
Hole distribution in (Tl0.5Pb0.5)Sr2(Ca1-xYx)Cu2O7 studied by x-ray absorption spectroscopy.
复制标题
通过X射线吸收光谱研究了(Tl0.5Pb0.5)Sr2(Ca1-xYx)Cu2O7中的空穴分布。
DOI：
10.1103/physrevb.54.12587
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Liang
中科院分区：
文献类型：
--
作者：
Chen;Liu;Liang
采用体敏感全荧光产率技术测量了一系列（Tl{sub 0.5}Pb{sub 0.5}）Sr{sub 2}(Ca{sub 1{-}{ital x}}Y{sub {ital x}})Cu{sub 2}O{sub 7}化合物（{ital x}=0{endash}0.9）的高分辨率O{ital K}边和Cu{ital L}{sub 23}边x射线吸收近边结构光谱。在O{ital s}边缘附近，观察到一个非常明显的前边缘峰，其最大值{约}528.3 eV，这是由于O{ital s}电子对位于CuO{sub 2}平面上的O{ital p}空穴的激发。当Ca掺杂量为0{le}{ital x}{le}0.5时，该前边峰的强度呈线性增加。这表明Ca{sup 2+}对Y{sup 3+}的化学取代作用是在费米能级附近的CuO{sub 2}平面上诱导空穴态，这对于控制（Tl{sub 0.5}Pb{sub 0.5}）Sr{sub 2}(Ca{sub 1{-}{ital x}}Y{sub {ital x}})Cu{sub 2}O{sub 7}化合物的{ital T}{sub {ital c}}具有重要意义。此外，在CuO{sub 2}平面内的o2 {ital p}轨道上产生的空穴可能是诱导从半导体到超导体转变的原因。在Cu {ital L}边缘吸收光谱中，933.1和952.9 eV的高能肩属于Cu(2{ital p}{sub 3/2,1/2})3{ital d}{sup 9}{ital L}基态到Cu(2{ital p}{sub 3/2,1/2}){sup{负}1}3{ital d}{sup 10}{ital L}激发态的跃迁，其中{ital L}表示O 2{ital p}配体空穴。这些缺陷态的归一化强度随Y位Ca化学浓度的增加呈线性增加。{版权所有}{ital 1996美国物理学会。}«少
High-resolution O {ital K}-edge and Cu {ital L}{sub 23}-edge x-ray-absorption near-edge-structure spectra for the series of (Tl{sub 0.5}Pb{sub 0.5})Sr{sub 2}(Ca{sub 1{minus}{ital x}}Y{sub {ital x}})Cu{sub 2}O{sub 7} compounds ({ital x}=0{endash}0.9) were measured using a bulk-sensitive total-fluorescence-yield technique. Near the O 1{ital s} edge, a well-pronounced pre-edge peak with maxima at {approximately}528.3 eV is observed, which is ascribed to the excitations of O 1{ital s} electrons to O 2{ital p} holes located in the CuO{sub 2} planes. The intensity of this pre-edge peak increases linearly with the Ca doping for 0{le}{ital x}{le}0.5. This indicates that the effect of chemical substitution of Ca{sup 2+} for Y{sup 3+} is to induce hole states in the CuO{sub 2} planes near the Fermi level, which are important to control the {ital T}{sub {ital c}} for the series of (Tl{sub 0.5}Pb{sub 0.5})Sr{sub 2}(Ca{sub 1{minus}{ital x}}Y{sub {ital x}})Cu{sub 2}O{sub 7} compounds. Moreover, the generation of holes in the O 2{ital p} orbitals within the CuO{sub 2} planes is probably responsible for inducing a transition from a semiconductor to a superconductor. In the Cu {ital L}-edge absorption spectra, high-energy shoulders at 933.1 and 952.9 eV are assigned to the transitions from the Cu(2{ital p}{sub 3/2,1/2})3{ital d}{sup 9}{ital L} groundmore » state to the Cu(2{ital p}{sub 3/2,1/2}){sup {minus}1}3{ital d}{sup 10}{ital L} excited state, where {ital L} denotes the O 2{ital p} ligand hole. The normalized intensity of these defect states shows a linear increase with increasing the chemical concentration of Ca in the Y sites. {copyright} {ital 1996 The American Physical Society.}« less