Magnetocrystalline Anisotropy Constants of Iron at Room Temperature and Below

The anisotropy constants of iron have been determined from torque measurements on a {100} single-crystal disk in fields up to 15 000 oersteds or higher and at temperatures of 77, 195, and 300°K. The values of $K_1$ at the three temperatures are (520±10)×${10}^3$, (505±10)×${10}^3$, and (480±10)×${10}^3$ ergs/${\mathrm{cm}}^3$; the value of $K_2$ at all three temperatures is (0±50)×${10}^3$ ergs/${\mathrm{cm}}^3$. The anisotropy decreases as the fourth power of the saturation magnetization over the temperature range studied.