Magnetotransport of La0.70Ca0.3−xSrxMnO3(Ag): A potential room temperature bolometer and magnetic sensor

Abstract

Here we report the optimized magnetotransport properties of polycrystalline La 0.70 Ca 0.3−x Sr x MnO 3 and their composites with Ag. The optimization was carried out by varying the Sr and Ag contents simultaneously to achieve large temperature coefficient of resistance ͑TCR͒ as well as low field magnetoresistance ͑MR͒ at room temperature. Sharpest paramagnetic ͑PM͒-ferromagnetic ͑FM͒ and insulator-metal ͑IM͒ transition is observed in the vicinity of the room temperature ͑T C Ϸ 300 K Ϸ T IM ͒ for the composition La 0.70 Ca 0.20 Sr 0.10 MnO 3 :Ag 0.20 . Partial substitution of larger Sr 2+ ions at the Ca 2+ ions sites controls the magnitude of the FM and IM transition temperatures, while the Ag induces the desired sharpness in these transitions. For the optimized composition, maximum TCR and MR are tuned to room temperature ͑300 K͒ with the former being as high as 9% and the later being ϳ20% and ϳ30% at 5 and 10 kOe magnetic fields respectively. Such sharp single peak ͑TCRϳ 9%͒ at room temperature can be used for the bolometric and infrared detector applications. The achievement of large TCR and low field MR at T ϳ 300 K in polycrystalline samples is encouraging and we believe that further improvements can be achieved in thin films which by virtue of their low conduction noise are more suitable for device applications.

Investigation of the critical behavior in Mn0.94Nb0.06CoGe alloy by using the field dependence of magnetic entropy change

“…[9][10][11] Since the magnetic properties of perovskite manganites, Curie temperature and saturation magnetization, are strongly doping-dependent, these typical materials are believed to be good candidates for magnetic refrigeration at various temperatures. 12,13 However, for different reasons, none of these materials have yet been employed in a commercial refrigerator. Obviously, there is a need for yet further improved materials.…”

Room temperature magnetic entropy change and magnetoresistance in La0.70(Ca0.30−xSrx)MnO3:Ag 10% (x=0.0−0.10)

“…Since magnetic refrigeration has a lot of advantages over gas refrigeration, manganites have been getting attention [4,[6][7]. Also, since the magnetic properties of perovskite 2 manganites, Curie temperature and saturation magnetization, are strongly doping-dependent, these typical materials are believed to be good candidates for magnetic refrigeration at various temperatures [5][6][7][8][9][10][11]. The magnetocaloric effect (MCE) is an isothermal magnetic entropy change or an adiabatic temperature change (∆T ad ) of a magnetic material caused by an applied magnetic field.…”

“…Manganites are considered to be promising candidate for the technological applications such as bolometer and magnetic refrigeration [1][2][3][4][5][6][7]. Along with the all other fascinating properties, the presence of magnetocaloric nature makes them more outstanding material.…”

“…A maximum 58 % change of MR can be seen with the change in applied field of 3 T at 270 K. Although it has better MR but the working temperature is far below room temperature. Earlier it is reported [5,7,11] with doping of Sr at Ca site the transition temperature increases and it is found around 308 K for Sr = 0.10. Although the T c increases with Sr doping but it is at the cost of sharpness of transition.…”

Observance of Improved Magneto-resistance and Magnetic Entropy Change in La0.7(Ca0.2Sr0.1)MnO3:Pd Composite

“…Colossal magneto-resistive (CMR) manganites have been considered to be promising candidates for wide range of applications like magnetic sensors, bolometric devices and magnetic refrigeration [1][2][3][4][5][6][7]. The interesting physical properties of the manganites are known to originate from a complex interplay among structural, electrical, and magnetic degrees of freedom.…”