Superconductivity in Amorphous Bismuth at Negative Pressures

Bismuth is a semimetal that has interesting properties depending on the structure in which it is found; one of these properties is superconductivity. At ambient pressure, superconductivity has been observed in the amorphous phase with a critical temperature, <i>T_c</i>, of 6 K, while for the crystalline phase it has a value below 0.53 mK [1], a result predicted by our group in 2016 [2]. A superconducting transition temperature of 2.61 K was also predicted by our group in 2018 for the bismuth bilayers [3]. Furthermore, we have studied the appearance of this phenomenon in bismuth under pressure and some results agree with experiments [4] while others are awaiting experimental verification [5, 6]. In this work we will investigate the effect of negative pressures on the superconductivity of the amorphous bismuth by <i>ab initio</i> calculations in supercells of 216 atoms with densities of 9.81 g/cm³, 9.34 g/cm³ and 8.53 g/cm³. Amorphous structures will be obtained through molecular dynamics and our <i>undermelt-quench</i> process that has given specimens in accord to the experiment [2]. We shall report electronic properties of such samples and draw conclusions.<br/> <br/>[1] O. Prakash, A. Kumar, A. Thamizhavel, S. Ramakrishnan. Evidence for bulk superconductivity in pure bismuth single crystals at ambient pressure. Science 355 (2017), pp. 52-55. DOI: 10.1126/science.aaf8227.<br/>[2] Z. Mata-Pinzón, A. A. Valladares, R. M. Valladares, A. Valladares. Superconductivity in Bismuth. A New Look at an Old Problem. PLoS ONE 11 (2016), e0147645. DOI:10.1371/journal.pone.0147645.<br/>[3] D. Hinojosa-Romero, I. Rodriguez, A. Valladares, R. M. Valladares, A. A. Valladares. Possible superconductivity in Bismuth (111) bilayers. Their electronic and vibrational properties from first principles. MRS Advances 3 (2018), pp. 313-319. DOI: 10.1557/adv.2018.119.<br/>[4] I. Rodríguez, D. Hinojosa-Romero, A. Valladares, R. M. Valladares, A. A. Valladares. A facile approach to calculating superconducting transition temperatures in the bismuth solid phases. Scientific Reports 9 (2019) 5256 DOI:10.1038/s41598-019-41401-z<br/>[5] D. Hinojosa-Romero, I. Rodriguez, Z. Mata-Pinzón, A. Valladares, R. M. Valladares, A. A. Valladares. Compressed Crystalline Bismuth and Superconductivity - An ab initio computational Simulation. MRS Advances 2 (2017), pp. 499-506. DOI: 10.1557/adv.2017.66<br/>[6] A. A. Valladares, I. Rodríguez, D. Hinojosa-Romero, A. Valladares, R. M. Valladares. Possible superconductivity in the Bismuth IV solid phase under pressure. Scientific Reports 8 (2018) 5946 DOI:10.1038/s41598-018-24150-3.