ENERGY GAPS MEASURED BY SCANNING TUNNELING MICROSCOPY
ENERGY GAPS MEASURED BY SCANNING TUNNELING MICROSCOPY
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DOI：
10.1103/physrevb.42.8890
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发表时间：
1990-11-15
影响因子：
3.7
通讯作者：
SUBRAMANIAN, MA
中科院分区：
文献类型：
--
作者：
CHEN, W;GIAMBATTISTA, B;SUBRAMANIAN, MA
利用扫描隧道显微镜（STM）测量了层状结构的二硫化物和高温超导体bi2sr2cacu2o8中电荷密度波（CDW）相的能隙。在4.2 K下，2H-TaSe 2、2H-TaS 2和2H-NbSe 2的Δ CDW测量值分别为80、50和34 meV，其值为2 Δ CDW/ kbtc分别为15.2、15.4和23.9，表明这些CDW系统中存在强耦合。在1T-TaSe 2和1T-TaS 2中，两种材料在4.2 K下的Δ CDW测量值为~ 150 meV，得到2 Δ CDW/ K B T c 5.8。STM扫描bi2sr2cacu2o8在4.2 K分辨原子在biox层和显示可能的电子结构的变化。由I/ V曲线和dI/dV / V曲线确定的能隙在30-35 meV范围内，其值为2Δ/k B T c 8。用STM进行光谱测量会出现较大的零偏异常，这使能隙结构的分析变得复杂，但已经完成了充分的分离。
A scanning tunneling microscope (STM) has been used to measure energy gaps in the charge-density-wave (CDW) phases of the layer-structure dichalcogenides and in the high-temperature superconductor Bi 2 Sr 2 CaCu 2 O 8. Measured values of Δ CDW at 4.2 K for 2H-TaSe 2, 2H-TaS 2, and 2H-NbSe 2 are 80, 50, and 34 meV giving values of 2 Δ CDW/k B T c equal to 15.2, 15.4, and 23.9, indicating strong coupling in these CDW systems. Measured values of Δ CDW at 4.2 K in 1T-TaSe 2 and 1T-TaS 2 are∼ 150 meV for both materials giving 2 Δ CDW/k B T c≊ 5.8. STM scans of Bi 2 Sr 2 CaCu 2 O 8 at 4.2 K resolve atoms on the BiO x layer and show possible variations in electronic structure. The energy gap determined from I versus V and dI/dV versus V curves is in the range 30–35 meV giving values of 2Δ/k B T c≊ 8. Spectroscopy measurements with the STM can exhibit large zero-bias anomalies which complicate the analysis of the energy-gap structure, but adequate separation has been accomplished.