Structure and pressure dependence of the Fermi surface of lithium*

There has been much interest in the phase diagram of lithium at both 1 atm and high pressure. We report first-principles calculations combined with Shubnikov–de Haas (SdH) oscillation measurements at 300 mK in external magnetic fields up to 35 T to map the Fermi surface of lithium.  At 1 atm, our data reveal direct evidence for its spherical deformation. As the pressure increases, the deformation increases, but the Fermi surface remains mostly spherical up to 4.7 GPa. Finally, our data indicate that the electron effective mass does not deviate significantly under compression from its ambient pressure value.