Effect of Co doping on magneto-transport properties of Eu0.50.5Sr0.50.5MnO33

• Eu0.5Sr0.5Mn1−xCoxO3 samples are found to be in Pbnm orthorhombic structure.
• Ground state properties of studied samples are sensitive to Co concentration.
• Except x = 0.1, all other samples show field induced insulator-metal transition.
• The samples show large (>99.9%) magnetoresistance below insulator-metal transition.
• Low temperature resistivity depends strongly on previous history of applied field.

The perovskite manganites of nominal composition Eu0.50.5Sr0.50.5Mn1-x1-xCoxxO33 (x = 0, 0.02, 0.05 and 0.1) were investigated through magnetic and electrical transport measurements. Ground state properties of studied compounds were found to be very much sensitive to the Co concentration. In zero magnetic field, all the compositions show insulating behavior down to the lowest temperature of measurement. On application of external magnetic field, samples start to show (except x = 0.1 composition) first order insulator-metal (IM) transition. Resistivity of the samples below IM transition depends strongly on the previous history of the applied magnetic field. Clear signature of magnetically arrested states was observed across the IM transition, which persists even when the samples were cooled down to 5 K. A large negative magnetoresistance is also present in the sample at the lowest temperature of measurements (well below the first order transition), which is possibly connected to the field induced transition of high resistive antiferromagnetic state to the low resistive ferromagnetic metallic state.