μ_5z or mu5z - initial impedance permeability¹⁾ approximating value of initial magnetic permeability μ_i obtained by measuring the relative magnetic permeability at the excitation of magnetic field strength H = 5 mOe = 0.005 Oe ≈ 0.4 A/m.²⁾³⁾

Therefore for the same material, rather confusingly, the value of μ5z defined at H = 5 mOe is practically very close to μ4z defined at H = 4 mA/cm = 0.4 A/m, which itself is identical to μ0.4z (because it is defined at H = 0.4 A/m).

• Types of magnetic permeability