Temperature and magnetic field dependence of the superconducting penetration depth in pure and impure aluminum single crystals

Measurements at about 0.9 MHz of the temperature dependence of the penetration depth in pure and impure single crystals of aluminum are found to be in substantial agreement with the calculations of Miller, while at the same time showing some anisotropy effects for the pure samples. The effect of a static magnetic field on the surface reactance at this frequency is found to be in substantial agreement for the pure samples with a model proposed by Garfunkel for extreme type-I superconductors. Near the superconducting transition temperature the effect of the static field is compared with the Ginzburg-Landau theory, with only limited success for the impure aluminum sample.