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 Delta X/X-o of -25.5% at 100 kHz, a giant magnetoimpedance Delta Z/Z(o) of -20% at 12 MHz and a giant AC magnetoresistance Delta R/R-o of -39.3% at 5 MHz under a very low field of 300 Oe at room temperature, whereas the DC magnetoresistance ??/?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 (Delta mu ''/mu ''(0) and Delta mu ''(phi)/mu ''(phi)(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 Delta mu ''/mu ''(0)=-25.8% and Delta mu ''(phi)/mu ''(phi)(0)=-10.9%. The values of ?R/R0 and ?Z/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 Delta mu ''/mu ''(0)=-24.9%, Delta mu ''(phi)/mu ''(phi)(0)=-49.8% at 1 MHz, and Delta mu ''/mu ''(0)=-21.2%, Delta mu ''(phi)/mu ''(phi)(0)=-58.2% at 5 MHz (C) 2010 Elsevier B.V. All rights reserved.