Giant magnetoimpedance and permeability change in La2/3Sr1/3MnO3 manganite under low fields

We demonstrated that La_2/3Sr_1/3MnO₃ sintered manganite could exhibit a magnetoreactance ΔX/X₀ of −25.5% at 100 kHz, a giant magnetoimpedance ΔZ/Z₀ of −20% at 1-2 MHz and a giant AC magnetoresistance ΔR/R₀ of −39.3% at 5 MHz under a very low field of 300 Oe at room temperature, whereas the DC magnetoresistance Δρ/ρ₀ was −3.95% under H=10 kOe and only about −0.18% under H=300 Oe. Large field-induced change of real and imaginary circular permeabilities (Δμ′_?/μ′_?(0) and Δμ″_?/μ″_?(0)) were obtained for La_2/3Sr_1/3MnO₃ sintered manganite. The giant magnetoreactance (giant magneto-inductive effect) at very low frequencies originates from the field induced change of transverse permeability. At 100 kHz under H=300 Oe, La_2/3Sr_1/3MnO₃ sintered manganite has Δμ′_?/μ′_?(0)=−25.8% and Δμ″_?/μ″_?(0)=−10.9%. The values of ΔR/R₀ and ΔZ/Z₀ are very small under 300 Oe at 100 kHz. The giant magnetoimpedance at high frequencies mainly originates from the large transverse permeability change induced by DC magnetic fields, via the penetration depth. Under H=300 Oe, La_2/3Sr_1/3MnO₃ sintered manganite presents values of Δμ′_?/μ′_?(0)=−24.9%, Δμ″_?/μ″_?(0)=−49.8% at 1 MHz, and Δμ′_?/μ′_?(0)=−21.2%, Δμ″_?/μ″_?(0)=−58.2% at 5 MHz.