4.6 Article

Evidence for increased metallicity arising from carbon-sulfur bonding and amorphization effects in sulfur-doped pyrolytic graphite

期刊

DIAMOND AND RELATED MATERIALS
卷 121, 期 -, 页码 -

出版社

ELSEVIER SCIENCE SA
DOI: 10.1016/j.diamond.2021.108729

关键词

HOPG; Sulfur-doping; Insulator; Metallicity

资金

  1. NSFC [11950410752]
  2. National Key R&D Program of China [2017YFA0303600]
  3. Science Speciality Program of Sichuan University [2020SCUNL210]
  4. Sichuan University [SCU201208]
  5. Fundamental Research Funds for the Central Universities [2021SCU12116]

向作者/读者索取更多资源

In this study, the electronic and magnetic properties of sulfur-doped highly-oriented-pyrolytic-graphite (HOPG) lamellae were investigated. The sulfur-doping process caused amorphization within hexagonal moire superlattices. Raman spectroscopy analysis revealed a dominant carbon-sulfur band. Temperature dependent electron paramagnetic resonance (T-EPR) showed shifts in the position of the differential absorption feature and anomalous signal broadening. Magnetometry results indicated the absence of superconductive transitions but a critical ferromagnetic temperature. Density functional theory (DFT) calculations showed that sulfur doping affected the system's metallicity.
We report a novel investigation of the electronic and magnetic properties of exfoliated lamellae of highly-oriented-pyrolytic-graphite (HOPG) doped with great excess of sulfur. The sulfur-doping process was achieved through annealing at T similar to 250 degrees C, similar to 500 degrees C and similar to 990 degrees C. The obtained lamellae were investigated by employing transmission electron microscopy (TEM), Raman point/map spectroscopy and temperature dependent electron paramagnetic resonance (T-EPR). HRTEM analyses of samples doped at T similar to 990 degrees C revealed an unusual amorphization-effect arising within hexagonal moire ' superlattices as a consequence of the sulfur-doping. Com-plete amorphization was found at T-500 degrees C. Raman-spectroscopy point/mapping analyses highlighted a dominant carbon-sulfur-band, appearing at Raman-Shifts of 1450 cm(-1). T-EPR of heavily doped samples revealed presence of shifts in the position of the pi-electron differential absorption feature together with an anomalous signal broadening at T-doping similar to 500 degrees C (from g similar to 1.99 to g similar to 2.10), while zero field cooled (ZFC) and field cooled FC superconducting quantum interference device (SQUID) magnetometry from 2 K to 300 K revealed a critical percolative ferromagnetic temperature at T similar to 25 K and the absence of superconductive transitions. Density functional theory (DFT) calculations applied to a Bernal (AB stacked) bilayer-graphene-system in presence of sulfur-bonding revealed a significant variation of the system-metallicity. We highlight the appear-ance of insulating states (E-gap of 0.325 eV) at sulfur concentrations of similar to 1%, which then vanish at similar to 5.5% of sulfur-doping, due to an enhanced degree of system-metallicity and a modification of the pi-bonding-and anti-bonding-signals.

作者

我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。

评论

主要评分

4.6
评分不足

次要评分

新颖性
-
重要性
-
科学严谨性
-
评价这篇论文

推荐

暂无数据
暂无数据