Studies On The Internal Fricton In Bulks And The Synthesis And Transport Properties In Thin Films Of Perovskite Manganese Oxides

The colossal magnetoresistance (CMR) behaviors in perovskite-manganese oxides have attracted great attention due to both fundamental theory of condensed matter physics and potential applications of CMR materials in magnetic devices, e.g., read and write heads for magnetic disks, magnetic random access memories as well as magnetic field sensors. Therefore, the study on CMR effect has become a focus of recent condensed physics and material science.In the paper, we briefly review some new progress and the potential application about the CMR materials. We discussed the physical performance of these kinds of materials. We explained the relationships between the peak of internal friction (IF) and the peak of electric resistances versus temperature by studying the crystal structure, electromagnetic transport properties, IF and dynamic modulus in manganese oxides La0.85MnO3. The IF peak temperature corresponding to resistance peak temperature and Curie temperature (an apparent turning point at susceptibility curve) can be ascribed to a transition from paramagnetic insulator to ferromagnetic metal, and we can interpret it by double exchange mechanism. We also studied the synthesis and magnetic-resistance behavior of La0.67Sr0.33MnO3 / La0.85MnO3 / La0.67Sr0.33MnO3 and La0.67Sr0.33MnO3/ LaMnO3 / La0.67Sr0.33MnO3tri-layer films and {La0.67Sr0.33MnO/ La0.85MnO3}15 and {La0.67Sr0.33MnO3 / LaMnO3}15 multi-layer films by DC magnetron sputtering. The results show that CMR effect in multi-layer films is lager than that in tri-layer films.