Giant magnetoimpedance and colossal ac magnetoresistance of a Cu coil wound on La0.67Sr0.33MnO3

We observed the giant magnetoimpedance and colossal ac magnetoresistance for a Cu coil wound on La0.67Sr0.33MnO3 under low dc magnetic fields. Even though the dc magnetoresistance ΔR/R0 for La0.67Sr0.33MnO3 plate is only −2.4% under H=12H=12 kOe, a Cu coil wound on La0.67Sr0.33MnO3 plate exhibits a colossal ac magnetoresistance ΔR/R0 of −93% at 10 MHz and a giant magnetoimpedance ΔZ/Z0 of −59% in a wide frequency range of 500 kHz–10 MHz under a longitudinal field H=600Oe. The transverse magnetoimpedance is weaker than the longitudinal one. The giant magnetoimpedance and colossal ac magnetoresistance for a Cu coil wound on La0.67Sr0.33MnO3 are connected with the variation of permeability induced by dc magnetic field.