过度掺杂的La1-xAgxMnO3室温磁电阻研究

对采用溶胶凝胶法制备的不同Ag含量的La1-xAgxMnO3样品进行了研究.观察到Ag的名义含量x为0.3和0.65的样品表现出显著的室温磁电阻,在1.8 T的外场下磁电阻(外加磁场后的电阻和未加磁场的电阻差值比上未加磁场的电阻值)分别达到-23.0%和-22.7%,接近实际应用要求.对其成因进一步分析后发现,在两种不同Ag含量的样品中出现的显著室温磁电阻效应,其形成原因并不相同.

Study on magnetoresistance of excessive doped La1-xAgxMnO3 at room temperature

By way of doping excessive Ag~(1 ) ion in LaMnO_3,it is found that on the sample's magnetoresistance curve two peaks appear when socalled x=0.3 and x=0.65 at room temperature.At H=1.8 T the sample's MR achieve-23.0% and22.7% respectively.However,it must be pointed out that the true Ag contents are usually less than the calculated contents,because Ag will separate out from samples.The huge magnetoresistance effect in the sample of x=0.3 seems to be independent of Agrich phase,while the huge magnetoresistance effect in the sample of x=0.65 has close correlation with Agrich phase.In the tested sample,Ag,perovskite and hole reach the optimum ratio,and so,lead to a strong fieldinduced enhancement in percolation.