Pure borocarbides suffer from limited superconducting potential due to intrinsic structural instability, requiring transition/alkali metals as dual-functional stabilizers and dopants. Here, by combining high-throughput screening with anisotropic Migdal-Eliashberg theory, we identify dynamically stable borocarbides where high-$T_c$ superconductivity predominately originates from $E$ symmetry-selective electron-phonon coupling (EPC). The six distinct superconducting gaps emerge from a staircase distribution or uncoupling of EPC strength $\rho \left({\lambda }_k^{el}\right)$ across each Fermi surface sheet, constituting a metal-free system with such high gap multiplicity. Crucially, dimensional reduction from bulk to surface strengthens $E$-symmetry EPC and enhances $T_c$ from 32 K [three-dimensional (3D) bulk] to 75 K (2D surface), a result that highlights structural confinement as a key design strategy for observing high $T_c$. External strain further optimizes the competition between EPC strength and characteristic phonon frequency to achieve $T_c>90$ K. This work reveals a systematic correlation between structural dimensionality and gap multiplicity and establishes borocarbide as a tunable platform to engineer both high-$T_c$ and multigap superconductivity.

Close

PrevNext

View figure in article

• Electron-phonon coupling
• Electronic structure
• Superconducting gap
• Superconductivity
• Density functional calculations
• Strain engineering