Abstract
The electrical transport behavior and magnetoresistance (MR) of a polycrystalline double layered manganite La1.2Sr1.4Ba0.4Mn2O7, synthesized by the sol-gel method, are investigated in the temperature range 4.2 K - 300 K. The sample exhibits an insulator-to-metal transition at 87 K (TIM) and the spin-glass (SG)-like behavior is observed below 50 K (TSG). The transport behavior is analyzed in the entire temperature range considering three different regions: paramagnetic insulating region (T>TIM), ferromagnetic metallic region (TSG IM) and antiferromagnetic insulating region (TSG) by fitting the temperature dependent resistivity data to the equations governing the conduction process in the respective temperature regions. The results show that the conduction at T>TIM follows Mott variable range hopping (VRH) process, while the two-magnon scattering process is evidenced at TSG IM which is suppressed with the applied magnetic field of 4 T. The low temperature conductivity data are also fitted with Mott VRH equation. The sample exhibits a large MR (≈45%) over a temperature range 5 K – 50 K and it shows ≈32% MR at 5 K with a magnetic field of 0.5 T.
Highlights
The discovery of colossal magnetoresistance (CMR) in Labased double layered (DL) manganites La2-2xSr1+2xMn2O7 has provided an opportunity to explore the interaction among spin, charge and lattice in reduced dimensions [1,2]
The results show that the conduction at T > TIM follows Mott variable range hopping (VRH) process, while the two-magnon scattering process is evidenced at TSG < T < TIM which is suppressed with the applied magnetic field of 4 T
We present the results obtained for La1.2Sr1.4Ba0.4Mn2O7 which exists in three different regions: paramagnetic insulating region, ferromagnetic metallic region and antiferromagnetic insulating region in the temperature range 4.2 K – 300 K with a main focus on its transport behavior
Summary
The discovery of colossal magnetoresistance (CMR) in Labased double layered (DL) manganites La2-2xSr1+2xMn2O7 has provided an opportunity to explore the interaction among spin, charge and lattice in reduced dimensions [1,2]. These materials show large values of MR at moderate magnetic fields and proved to be promising materials for many technological applications. One can expect that the slight changes in the size and/or concentration of (La,A) site ions can show significant effect on bulk transport and magnetic properties. We present the results obtained for La1.2Sr1.4Ba0.4Mn2O7 which exists in three different regions: paramagnetic insulating region, ferromagnetic metallic region and antiferromagnetic insulating region in the temperature range 4.2 K – 300 K with a main focus on its transport behavior
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