Giant magnetoimpedance and permeability change in La 2/3Sr 1/3MnO 3 manganite under low fields

Abstract

We demonstrated that La 2/3Sr 1/3MnO 3 sintered manganite could exhibit a magnetoreactance Δ X/ X 0 of −25.5% at 100 kHz, a giant magnetoimpedance Δ Z/ Z 0 of −20% at 1–2 MHz and a giant AC magnetoresistance Δ R/ R 0 of −39.3% at 5 MHz under a very low field of 300 Oe at room temperature, whereas the DC magnetoresistance Δ ρ/ ρ 0 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 ( Δ μ ′ ϕ / μ ′ ϕ (0) and Δ μ ″ ϕ / μ ″ ϕ (0)) were obtained for La 2/3Sr 1/3MnO 3 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 1/3MnO 3 sintered manganite has Δ μ ′ ϕ / μ ′ ϕ (0)=−25.8% and Δ μ ″ ϕ / μ ″ ϕ (0)=−10.9%. The values of Δ R/ R 0 and Δ Z/ Z 0 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 1/3MnO 3 sintered manganite presents values of Δ μ ′ ϕ / μ ′ ϕ (0)=−24.9%, Δ μ ″ ϕ / μ ″ ϕ (0)=−49.8% at 1 MHz, and Δ μ ′ ϕ / μ ′ ϕ (0)=−21.2%, Δ μ ″ ϕ / μ ″ ϕ (0)=−58.2% at 5 MHz.