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Transition from tunneling regime to local point contact realized on Ba_(0.6)K_(0.4)Fe_2As_2 surface 下载免费PDF全文
Using scanning tunneling spectroscopy, we studied the transition from tunneling regime to local point contact on the iron-based superconductor Ba_(0.6)K_(0.4)Fe_2As_2. By gradually reducing the junction resistance, a series of spectra were obtained with the characteristics evolving from single-particle tunneling into Andreev reflection. The spectra can be well fitted to the modified Blonder–Tinkham–Klapwijk(BTK) model and exhibit significant changes of both spectral broadening and orbital selection due to the formation of point contact. The spatial resolution of the point contact was estimated to be several nanometers, providing a unique way to study the inhomogeneity of unconventional superconductors on such a scale. 相似文献
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The far-infrared optical reflectivity of an optimally doped Ba1-xKxFe2As2(x =0.4) single crystal is measured from room temperature down to 4 K. We study the temperature dependence of the in-plane infrared-active phonon at 251 cm-1 . This phonon exhibits a symmetric line shape in the optical conductivity, suggesting that the coupling between the phonon and the electronic background is weak. Upon cooling down, the frequency of this phonon continuously increases, following the conventional temperature dependence expected in the absence of a structural or magnetic transition. The intensity of this phonon is temperature independent within the measurement accuracy. These observations indicate that the structural and magnetic phase transition might be completely suppressed by chemical doping in the optimally doped Ba0.6K0.4Fe2As2 compound. 相似文献
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The far-infrared optical reflectivity of an optimaUy doped Ba1-xKxFe2As2 (x = 0.4) single crystal is measured from room temperature down to 4 K. We study the temperature dependence of the in-plane infrared-active phonon at 251 em-1. This phonon exhibits a symmetric line shape in the optical conductivity, suggesting that the coupling between the phonon and the electronic background is weak. Upon cooling down, the frequency of this phonon continu- ously increases, following the conventional temperature dependence expected in the absence of a structural or magnetic transition. The intensity of this phonon is temperature independent within the measurement accuracy. These observa- tions indicate that the structural and magnetic phase transition might be completely suppressed by chemical doping in the optimally doped Bao.6Ko.4Fe2As2 compound. 相似文献
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Sizable Residual Quasiparticle Density of States Induced by Impurity Scattering Effect in Ba(Fe1-xCox)2As2 Single Crystals 下载免费PDF全文
Low-temperature specific heat Cp is measured on Ba(Fe1-xCox)2As2 single crystals in a wide doping region. A sizeable residual specific heat coefficient γo is observed in the low temperature limit of all samples. The specific heat jump near Tc, i.e. ΔCp/T/T_c, is also determined. It is found that -γo, ΔCp/T/T_c and Tc all share a similar evolution with doping. These can be well understood within the model of S± pairing symmetry when accounting for the cobalt-dopants as unitary scattering centers in the FeAs planes. Our results reveal a non-trivial impact of impurity scattering in FeAs-based. 相似文献
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Evolution of the 251 cm<sup>-1</sup> infrared phonon mode with temperature in Ba<sub>0.6</sub>K<sub>0.4</sub>Fe<sub>2</sub>As<sub>2</sub> 下载免费PDF全文
The far-infrared optical reflectivity of an optimally doped Ba1-xKxFe2As2(x =0.4) single crystal is measured from room temperature down to 4 K. We study the temperature dependence of the in-plane infrared-active phonon at 251 cm-1 . This phonon exhibits a symmetric line shape in the optical conductivity, suggesting that the coupling between the phonon and the electronic background is weak. Upon cooling down, the frequency of this phonon continuously increases, following the conventional temperature dependence expected in the absence of a structural or magnetic transition. The intensity of this phonon is temperature independent within the measurement accuracy. These observations indicate that the structural and magnetic phase transition might be completely suppressed by chemical doping in the optimally doped Ba0.6K0.4Fe2As2 compound. 相似文献
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带有甘露糖的聚双炔薄膜能够识别大肠杆菌并与它们结合,更重要的是结合可以导致聚双炔薄膜的颜色发生改变,这种颜色变化很容易用裸眼观察到并且可以通过可见吸收光谱定量分析。这种通过聚双炔薄膜对分子识别的直接检测方法不仅为该薄膜在生物传感器发展领域中的应用开辟了一条新途径,而且为诊断应用和筛选新的连接配体提供了可能。此外,为了理解颜色变化的机理,我们用共振喇曼光谱和傅立叶变换红外光谱对聚双炔的亲合变色特性进行了检测。结果表明:当由蓝到红的颜色变化发生时,聚合物骨架的侧链进行了重新排列,同时聚合物骨架的电子结构由炔的形式转变为三烯的形式。 相似文献
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Mengwu Huo 《中国物理 B》2022,31(10):107401-107401
Superconductivity has been realized in films of La1-xSrxNiO2. Here we report synthesis and characterization of polycrystalline samples of La1-xSrxNiO3 and La1-xSrxNiO2 (0 ≤ x ≤ 0.2). Magnetization and resistivity measurements reveal that La1-xSrxNiO3 are paramagnetic metal and La1-xSrxNiO2 exhibit an insulating behavior. Superconductivity is not detected in bulk samples of La1-xSrxNiO2. The absence of superconductivity in bulk La1-xSrxNiO2 may be due to the generation of hydroxide during reduction, a small amount of nickel impurity, or incomplete reduction of apical oxygen. The effect of interface in films of La1-xSrxNiO2 may also play a role for superconductivity. 相似文献
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