Silicene and Germanene as Prospective Playgrounds for Room Temperature Superconductivity

Abstract

Combining theory and certain striking phenomenology we suggest that silicene and germanene are elemental Mott insulators and abode of doping induced high Tc superconductivity. In our theory, a 3 fold reduction in silicene π-π * band width, in comparison to graphene, and short range coulomb interactions enable Mott localization. Recent experimental results are invoked to provide support for our Mott insulator model: i) a significant π-band narrowing, in silicene on ZrB2 seen in ARPES, ii) a superconducting gap appearing below 35 K with a large 2∆ k B T c ∼ 20 in silicene on Ag, iii) emergence of electron like pockets at M points, on electron doping by Na adsorbent, iv) certain coherent quantum oscillation like features exhibited by silicene transistor at room temperatures and v) absence of Landau level splitting upto 7 Tesla and vi) superstructures, not common in graphene but, ubiquitous in silicene. A synthesis of the above results using theory of Mott insulator, with and without doping, is attempted. We surmise that if competing orders are taken care of and optimal doping achieved, superconductivity in silicene and germanene could reach room temperature scales; our estimates of model parameters, t and J ∼ 1 eV, are encouragingly high, compared to cuprates.

Germanium‐based monoelemental and binary two‐dimensional materials: Theoretical and experimental investigations and promising applications

“…In germanene, In germanene, massless Dirac fermions are the charge carriers, and the predicted intrinsic carrier mobility is 6 × 10 5 cm 2 V −1 s −1 , 69 which is a significantly large value and makes germanene a good complement to graphene or silicene in the nanoindustry. In addition, theoretical calculations also show that the buckled HC structure of germanene exhibits a quantum spin Hall effect (QSHE), 28 and doping facilitates high‐temperature superconductivity in this 2D material 70 …”

“…In addition, theoretical calculations also show that the buckled HC structure of germanene exhibits a quantum spin Hall effect (QSHE), 28 and doping facilitates high-temperature superconductivity in this 2D material. 70 Although it has been predicted that the monolayer hexagonal structure of germanene is stable in its freestanding form, synthesizing germanene is still a considerably challenging task. Unlike graphene, which can be exfoliated from graphite, it was believed that germanene has no counterpart material, from which it can be directly peeled off.…”

“…As a result, the family of Ge-based 2D materials has emerged with various interesting properties and applications. In addition to the abovementioned properties, the strong electron-phonon couplings of the monolayer Ge-based materials aid in the realization of superconductivity, 70,221,[646][647][648][649][650] and the low thickness and ultra-small aperture of the 2D material films make them suitable for gas separation. [651][652][653]…”

Superconductivity in silicon

“…Apart from this, there are discrepancies on the claim of silicene to be Dirac semimetal similar to graphene. In a report by Baskaran, it was proposed that silicene behaves as an elemental Mott insulator instead of Dirac semimetal [51]. In the paper, a short range coulomb interactions and threefold reduction in π − π * band width of silicene leads to Mott localization.…”

Phase transitions in the binary-alloy Hubbard model: Insights from strong-coupling perturbation theory

“…The correlation effects in the honeycomb lattice have been widely investigated which result in a number of exotic phenomena in both theory and experiment such as the correlated electrons in the graphene [26,27] and Silicene [28][29][30][31] as well as topological Mott insulator [32]. Combination of disorder and correlation gives rise to other interesting phenomena such as the formation of AI phases and possible transitions to metallic behavior driven by interactions.…”