COLOSSAL MAGNETORESISTANCE BOLOMETER
超巨磁阻测辐射热仪

Based on the sharp resistance change near the metal-insulator transition (M-I) of the colossal magnetoresistance (CMR) materials, we design and test a new type CMR bolometer. La0.67Ca0.33MnO3 epitaxial thin films were used as the photosensitive element of the bolometer, and the optical response of this device to the He-Ne laser and the blackbody were measured. The measured signal and noise decrease with increasing modulation frequency; however, the signal-to-noise ratio shows no obvious change for the He-Ne laser. The temperature dependence of signal was measured in both ferromagnetic metallic and paramagnetic insulating states. It shows that the strongest signal appears in the ferromagnetic state very close to the M-I point. The film's Curie temperature can span from 70 to 350K, depending on the manufacture conditions. So, working near or at room temperature characterizes this CMR thin film bolometer. In this sense, it compensates the weakness of the high-temperature superconductor bolometer that can be used only around the liquid Nitrogen (LN) temperature.The measured detectivity is about 107 cmHz1/2/W and the thermal response constant is 20ms for this device. Compared with the high-temperature superconductor bolometer, the time constant of CMR bolometer is longer and the detectivity is lower. However, there is much room to improve yet.