Superconductivity in molecule-intercalatedLixZrNClwith variable interlayer spacing

Abstract

Specific heat has been investigated in electron-doped Li x M y ZrNCl superconductors, in which interlayer spacing d can be controlled by the intercalation of organic molecules M. It has been revealed that, upon enlargement of d by molecule cointercalation, T c is enhanced concomitantly with the superconducting coupling strength whereas the density of states at the Fermi level is kept almost constant. Structural and spectroscopic analysis proved that the molecules are intercalated without affecting electronic nor vibrational states, simply increasing the interlayer spacing. These results lead us to conclude that the enhancement of T c is ascribed to the improvement of two dimensionality, which is consistent with a recent theory that discussed superconductivity in a band insulator on a honeycomb lattice with disconnected Fermi surfaces.

Unconventional superconductivity in electron-doped layered metal nitride halides MNX (M= Ti, Zr, Hf; X= Cl, Br, I)

“…With further increasing d, T c remains constant or decreases [39,40]. The specific heat measurements of Li x (Solv) y ZrNCl have revealed that the enhancement of T c is ascribed to concomitant enhancement of the pairing interaction [40]. Based on these results, it is concluded that the pairing interaction strongly depends on the Fermi surface warping along the k z direction, implying the relevance of charge and/or spin fluctuations rather than phonons.…”

“…The highest T c = 26.0 K is obtained in Ca 0.11 (THF) y HfNCl [33]. With further increasing d, T c remains constant or decreases [39,40]. The specific heat measurements of Li x (Solv) y ZrNCl have revealed that the enhancement of T c is ascribed to concomitant enhancement of the pairing interaction [40].…”

Dielectric response of electron-doped ionic superconductorLixZrNCl

“…Large organic molecules may also be included. [7][8][9] However, the origin of the high T c remains unknown, as the characteristics of this class of superconductors are unique. There is a low DOS at the Fermi level and a weak electron phonon cou- pling has been suggested both experimentally 10,11 and theoretically.…”

Electrochemical doping of few-layer ZrNCl from first principles: Electronic and structural properties in field-effect configuration

“…, are the monopole, dipole, and potential barrier, given in Eqs. (5), (9), and (11), respectively. The different parts of the Kohn-Sham potential are also shown in Fig.…”

“…In recent years, materials with reduced dimensionality have attracted a lot of attention because of their interesting physical properties and proposed applications range from electronics to sensing. In addition to graphene, which is probably the most studied two-dimensional (2D) material, monolayers or few-layer systems (nanolayers) of layered materials such as transition metal dichalcogenides [1][2][3][4][5][6][7] or chloronitrides [8][9][10][11][12] are gaining importance because of their intrinsic band gap. The possibility of doping these few layer systems with field-effect transistors (FETs) is particularly appealing.…”