La–Sr–Mn–Co–O Films for High Pulsed Magnetic Field Measurements at Cryogenic Temperatures

The magnetoresistance of nanostructured La
_1-x
Sr
_x
(Mn
_1-y
Co
_y
)
_z
O
_3±δ
(La-Sr-Mn-Co-O) films with substitution of Co for Mn with amount of Co/(La + Sr) = 0.12 and different Mn excess Mn/(La + Sr) = 1.05, 1.07, and 1.11 was investigated at temperatures of 4-230 K in pulsed magnetic fields up to 60 T. It was found that the manganite-cobaltite films exhibit larger magnetoresistance in comparison with manganite films without Co doping. The largest magnetoresistance values and sensitivity to the magnetic field are obtained for La-Sr-Mn-Co-O films having Mn content close to the stoichiometric ratio for manganites: Mn/(La + Sr) = 1.05. It was found that magnetoresistance at high fields (20-60 T) has a minimum at (50-80 K) and increases with the decrease of temperature. The possibility to use these films for magnetic field measurements at cryogenic temperatures is demonstrated.