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

We demonstrated that La2/3Sr1/3MnO3 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′ϕΔμ′ϕ/μ′ϕμ′ϕ(0) and Δμ″ϕΔμ″ϕ/μ″ϕμ″ϕ(0)) were obtained for La2/3Sr1/3MnO3 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, La2/3Sr1/3MnO3 sintered manganite has Δμ′ϕΔμ′ϕ/μ′ϕμ′ϕ(0)=−25.8% and Δμ″ϕΔμ″ϕ/μ″ϕμ″ϕ(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, La2/3Sr1/3MnO3 sintered manganite presents values of Δμ′ϕΔμ′ϕ/μ′ϕμ′ϕ(0)=−24.9%, Δμ″ϕΔμ″ϕ/μ″ϕμ″ϕ(0)=−49.8% at 1 MHz, and Δμ′ϕΔμ′ϕ/μ′ϕμ′ϕ(0)=−21.2%, Δμ″ϕΔμ″ϕ/μ″ϕμ″ϕ(0)=−58.2% at 5 MHz.