Abstract
We report the magnetic field dependence of electrical impedance (magnetoimpedance) of a ferromagnetic Pr0.6Sr0.4MnO3 sample carrying alternating current (ac) of frequency f = 1 MHz to 3 GHz measured using an impedance analyzer and broad band ferromagnetic resonance (f = 2 to 18 GHz) measured using a coplanar wave guide based spectrometer. Ac magnetoresistance is much larger than dc magnetoresistance and its sign at low magnetic fields changes from negative to positive with increasing frequency of the ac current. The field dependence of ac magnetoresistance shows a peak around Hdc = 0 for low frequencies but a double peak feature emerges at Hdc = ±Hp at higher frequencies and it shifts to higher magnetic field as the frequency of ac current increases. The field derivative of microwave power absorption measured by the broad band spectrometer shows features of ferromagnetic resonance and the resonance field increases with increasing frequency of microwave radiation following Kittel's equation for ferromagnetic resonance. A close correlation is found between the ferromagnetic resonance line shape and the positive peak in the ac magnetoresistance, which suggests the possibility of electrical detection of ferromagnetic resonance using high frequency current injected into a conducting magnetic sample.
Highlights
The Mn-based perovskites known as manganites (R1ÀxAxMnO3 where R 1⁄4 La3+, Pr3+, etc., and A 1⁄4 Sr2+, Ca2+ etc.) have been extensively studied over the last three decades because of the two most exciting physical phenomena exhibited by them: colossal negative magnetoresistance for lighter rare earth ions (R 1⁄4 La, Pr, Nd)[1,2] and spin-driven ferroelectricity in parent RMnO3 for heavy rare earth ions (R 1⁄4 Tb, Tm, Y).[3]
Microwave magnetoresistance was estimated from changes in microwave re ectivity of the cavity in absence and in presence of a dc magnetic eld. In contrast to these reports, here, we report microwave magnetotransport in Pr0.6Sr0.4MnO3 by passing alternating current of frequency f through the sample and measuring its electrical impedance in presence of an external dc magnetic eld
Our results indicate that high frequency magnetoimpedance shows features of ferromagnetic resonance (FMR)
Summary
The Mn-based perovskites known as manganites (R1ÀxAxMnO3 where R 1⁄4 La3+, Pr3+, etc., and A 1⁄4 Sr2+, Ca2+ etc.) have been extensively studied over the last three decades because of the two most exciting physical phenomena exhibited by them: colossal negative magnetoresistance for lighter rare earth ions (R 1⁄4 La, Pr, Nd)[1,2] and spin-driven ferroelectricity in parent RMnO3 for heavy rare earth ions (R 1⁄4 Tb, Tm, Y).[3] Parent compounds (RMnO3) possessing only Mn3+ ions are antiferromagnetic insulators whereas divalent cation substituted compounds containing mixed valent ions (Mn3+: t32ge1g and Mn4+: t32ge0g) are ferromagnetic metals for x 1⁄4 0.2–0.45 and antiferromagnetic insulators for 0.5 # x # 1 for R 1⁄4 La. The compositional range for ferromagnetism shrinks and ferromagnetic Curie temperature decreases as the ionic radius of R ion decreases. The in uence of magnetic eld on resistivity is greatest at the paramagnetic–ferromagnetic phase boundary. 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 1⁄4 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
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
