The Predicted fcc Superconducting Phase for Compressed Se and Te

Abstract

In the framework of the ab initio random structure search method, we show that elemental Se and Te undergo pressure-induced structural transition from the bcc to fcc phase, in agreement with the theoretical results previously reported. By means of the pseudopotential plane-wave method based on density functional perturbation theory, the fcc structure for both elements is found to be another phonon-mediated superconducting phase of these materials. With a reasonable value for the Coulomb pseudopotential 𝜇 * = 0.12, the maximum superconducting transition temperature 𝑇c in the fcc phase of Se and Te is estimated to be about 5.7 K and 4.6 K, respectively. Furthermore, we show that in the entire fcc phase for Se and Te, the superconducting transition temperature decreases together with the increase in pressure, leading to the final suppression of the superconductivity. It is suggested that such behavior is mainly caused by the rapid increase in the mean-square phonon frequency ⟨𝜔 2 ⟩ with pressure. Finally, a very strong electron-phonon coupling value, for both Se and Te in the fcc phase, is found along the 𝐺-𝐾 high symmetry lines.

Two ultra-stable novel allotropes of tellurium few-layers*

“…Tellurium few-layers are a category of emerging group VI 2D layers. [39][40][41][42][43][44][45][46][47][48][49] The few-layer α phase, cleavable from its bulk counterpart, shows amazing electronic, optical, vibrational, and topological properties [50][51][52] and can be synthesized using wet-chemistry methods. [41] Therefore, the synthesis of it does not need a substrate while other 2D few-layers need either exfoliation from their bulk counterparts [4][5][6][19][20][21][53][54][55] or substrates to stabilize [17,[56][57][58][59][60] the synthesis of layered samples.…”

Study of the High-Pressure Superconducting State in H3Se at 300 GPa

“…Interestingly, the latter one is not the * corresponding author; e-mail: edrzazga@wip.pcz.pl sole similarity shared by hydrogen-based superconductors with selenium and sulphur, respectively. In particular, both selenium [10,11] and sulfur [12,13] are predicted to be superconducting as a standalone chemical elements. Furthermore, selenium is a similar and isoelectronic to sulfur; both are chalcogenides in the same group of periodic [2,14], and PtH [16][17][18][19].…”

On the critical temperature discontinuity at the theoretical bcc-fcc phase transition in compressed selenium and tellurium superconductors

“…The elements of group VIa, or chalcogens, are known to present multiple interesting properties under the influence of pressure [1], where one of them is the possibility of generating superconducting phase in these materials [2]. In this respect, the most intriguing members of chalcogen group are sulfur (S), selenium (Se), and tellurium (Te), which allows induction of the superconducting state with relatively high critical temperature (T C ) values [2][3][4]. In addition to that, listed chalcogens exhibit potential for pairing with solid hydrogen, which is theoretically predicted to present the highest T C value among all the elements [5,6].…”

“…The already mentioned superconducting properties of Se and Te suggest that both materials can constitute a perspective sulfur counterpart elements for such applications. On its own, both Se and Te elements has been reported, on the basis of experimental [2,[12][13][14] and theoretical [4,[15][16][17] invest igations, to present superconducting properties which strongly depends on the applied external pressure. Simultaneously, with increasing pressure discussed elements present multiple crystal structure transitions, with similar sequence [2,14,18,19].…”