Ru⁴⁺ induced colossal magnetoimpedance in Ru doped perovskite manganite at room temperature

Abstract

We have demonstrated Ru(4+) induced colossal magnetoimpedance (MI) at room temperature in a ∼1 Tesla magnetic field with a pulsed laser deposited La0.7Ca0.3Mn0.7Ru0.3O3 thin film. This composition showed a large negative ∼12% MI in the low frequency range (<5 MHz), a colossal positive MI > 120% in the intermediate frequency range (5 MHz to ∼13 MHz) and a negative MI in the high frequency range (∼13 MHz to 40 MHz) at room temperature. XAS data confirmed the predominant Ru valence state was 4+ in La0.7Ca0.3Mn0.7Ru0.3O3. Ru(4+) induced (i) charge carrier localization and (ii) reduced hole carrier density enhances the MI in this composition, which otherwise was not significant in mixed valences Mn(3+)/Mn(4+) containing La0.7Ca0.3MnO3 and Ru(4+)/Ru(5+) and Mn(3+)/Mn(4+) mixed valences containing Ru = 0.1 and Ru = 0.2 compositions in La0.7Ca0.3Mn1-xRuxO3 (0 ≤x≤ 0.3) thin films.

Current controlled switching of impedance in magnetic conductor with tilted anisotropy easy axis and its applications

“…High and sensitive MI effect requires certain well established magnetic anisotropy and small anisotropy constant. For instance, the MI effect has been recently investigated in perovskite magnetic oxides2223. The reported values of MI effect are in the range of tens percents in the frequency range from a few thousands kHz to MHz that limits their application to only low access speed ones.…”

Ru doping effect on the structural, electronic, transport, optical and dye degradation properties of layered Li2MnO3

“…Presence of mixed valence Ru +4 /Ru +5 with Mn +3 /Mn +4 brings long range of magnetic ordering in La 0.7 Ca 0.3 Mn 1−x Ru x O 3 thin films [14]. Ru +4 containing thin film of La 0.7 Ca 0.3 Mn 0.7 Ru 0.3 O 3 shows colossal magnetoimpedance effects at room temperature [20]. Ru exists in its single valence state Ru +4 in LaMn 1−x Ru x O 3 (x = 0.1,0.2,0.3, 0.4) compositions and it shows band gad in the range of ~ 1.27 eV to 1.36 eV [21].…”

Microwave magnetoimpedance and ferromagnetic resonance in Pr0.6Sr0.4MnO3

“…Magnetoresistance in response to an alternating current (ac) through the sample barely received attention despite some claims of remarkable enhancement in the magnitude of ac magnetoresistance in the radio frequency regime (f ¼ 1-15 MHz) compared to dc magnetoresistance in a eld of few hundreds of Oersted. [4][5][6][7][8] Such a large enhancement in the ac magnetoresistance with alternating currents has potential for practical applications compared to the dc magnetoresistance if the low-eld sensitivity can be further improved.…”