Two-dimensional layered semiconductor black phosphorus (BP), a promising pressure induced Dirac system as predicted by band structure calculations, has been studied by 31P-nuclear magnetic resonance. Band calculations have been also carried out to estimate the density of states D(E). The temperature and pressure dependences of nuclear spin lattice relaxation rate 1/T1 in the semiconducting phase are well reproduced using the derived D(E), and the resultant pressure dependence of semiconducting gap is in good accordance with previous reports, giving a good confirmation that the band calculation on BP is fairly reliable. The present analysis of 1/T1 data with the complemental theoretical calculations allows us to extract essential information, such as the pressure dependences of D(E) and chemical potential, as well as to decompose observed 1/T1 into intrinsic and extrinsic contributions. An abrupt increase in 1/T1 at 1.63GPa indicates that the semiconducting gap closes, resulting in an enhancement of conductivity.
@article{arxiv.1905.05511,
title = {Pressure induced evolution of band structure in black phosphorus studied by $^{31}$P-NMR},
author = {T. Fujii and Y. Nakai and Y. Akahama and K. Ueda and T. Mito},
journal= {arXiv preprint arXiv:1905.05511},
year = {2020}
}