Unusual field dependence of radio frequency magnetoimpedance in La0.67Ba0.33MnO3A. Rebello and R. Mahendiran
Department of Physics and NUS Nanoscience & Nanotechnology Initiative (NUSNNI), Faculty of Science, National university of Singapore - 2 Science Drive 3, Singapore 117542, Singapore
received 24 November 2008; accepted in final form 30 March 2009; published April 2009
published online 6 May 2009
Magnetic-field dependence of the ac impedance Z(f,H) = R(f,H) + jX(f, H) in La0.67Ba0.33MnO3 carried out over a wide frequency range (f = 0 to 30 MHz) reveals a huge low-field ac magnetoresistance, R/R = -55% at f = 15 MHz and magnetoreactance, X/X = -80% at f = 3 MHz in = 100 mT at room temperature. We show contrasting evolution of R/R and X/X with increasing magnetic field and frequency. While R/R is negative and shows a single peak at = 0 T for all but f = 30 MHz, the single peak in X/X transforms into a valley at the origin and a double peak at H = Hk which shifts upward in H with increasing frequency. The X/X eventually changes sign from negative to positive above 25 MHz. The observed features in X/X suggest possible occurrence of ferromagnetic resonance in MHz range.
75.47.Lx - Manganites.
72.15.Gd - Galvanomagnetic and other magnetotransport effects.
72.25.Ba - Spin polarized transport in metals.
© EPLA 2009