Effect of boron dimers on the superconducting critical temperature in boron-doped diamond

We study how attractive boron correlations in boron-doped diamond affect the superconducting critical temperature. The critical temperature is obtained from the McMillan formula for strong coupling superconductors with the density of states evaluated in the dynamical cluster approximation. Numerical results for the cluster of 2 × 2 × 2 atoms show that attractive correlations lower the density of states at the Fermi level. We argue that this might explain experimentally observed differences in critical temperatures of 100 and 111 oriented films.

► Superconducting critical temperature of boron-doped diamond strongly depends on a growth orientation of samples. ► Within DCA we numericaly calculate that dimers and other boron complexes reduce the density of states at Fermi energy. ► This affects the superconducting critical temperature. ► Different density of boron dimers is able to describe the discrepancy in critical temperature of 111 and 100 samples.