Superconductivity and Unusual Magnetic Features in Amorphous Carbon and in Other Unrelated Materials

详细信息    查看全文

• 作者：Israel Felner
• 关键词：Amorphous carbon ; Superconductivity ; Peculiar magnetic behavior
• 刊名：Journal of Superconductivity and Novel Magnetism
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：30
• 期：1
• 页码：55-61
• 全文大小：
• 刊物类别：Physics and Astronomy
• 刊物主题：Strongly Correlated Systems, Superconductivity; Magnetism, Magnetic Materials; Condensed Matter Physics; Characterization and Evaluation of Materials;
• 出版者：Springer US
• ISSN：1557-1947
• 卷排序：30

文摘

Traces of superconductivity (SC) were observed in three different inhomogeneous sulfur-doped amorphous carbon (a-C) systems: (i) in old commercial powder, (ii) in fabricated (by pyrolytic decomposition of sucrose) powder, and (iii) in a-C thin films. (i) The commercial a-C powder contains 0.21 at% sulfur and reveals traces of two superconducting phases around T_C ˜34 and T_C∼65 K. (ii) The fabricated a-C powder is diamagnetic but not superconducting. However, mixtures of this powder with sulfur (a-CS) which were heated to 250 °C also show traces of SC up to T_C∼42 K. (iii) Non-superconducting a-C thin films were grown by electron-beam induced deposition. SC at T_C∼34 K emerged only after heat treatment with sulfur. It is proposed that the high SC states in a-CS (T_C∼65 K at ambient pressure) and in H₃S materials (T_C = 203 K under >200 GPa) has the same origin. In both sulfur-containing systems, SC is induced by the interaction between electrons and the high frequencies of low mass atom (H or C) vibrations a-CS products obtained by heating commercial and fabricated a-C powders at 400 °C show unusual magnetic features: (a) pronounced irreversible peaks around 55–80 K which appear in the first zero-field-cooled (ZFC) runs only. This temperature range is close to the highest T_C observed. (b) These peaks are totally suppressed in the second ZFC sweeps measured a few minutes later. (c) The peaks reappear after 18 months. (d) Around the peak position, the field-cooled (FC) curves cross the ZFC plots (ZFC > FC). All these phenomena are intrinsic properties of the amorphous carbon materials and were not observed in crystalline graphite. The ZFC > FC state was also observed in chiral-based magnetic memory device and unexpectedly in the liver taken from a patient with mantle cell lymphoma. This peculiarity will be discussed.