氧欠缺对La_(0.7)Ca_(0.3)Mn_(0.92)Cr_(0.08)O_(3-δ)电磁性质的影响  

EFFECTS OF OXYGEN DEFICIENCY ON THE MAGNETIZATION AND RESISTIVITY IN La_(0.7)Ca_(0.3)Mn_(0.92)Cr_(0.08)O_(3-δ)

作　　者：田建军[1] 方军[1] 王芳[1] 黄真[1] 陈治友[1] 陈敬林[1] 

机构地区：[1]中国科学院等离子体物理研究所强磁场实验室,合肥230031

出　　处：《低温物理学报》2004年第3期251-256,共6页Low Temperature Physical Letters

摘　　要：通过控制降温的方法 ,我们制备了一系列不同氧含量的La0 .7Ca0 .3Mn0 .92 Cr0 .0 8O3-δ多晶样品 ,并对其进行了X射线衍射谱、电阻温度关系和磁化强度以及磁电阻测量 .实验发现 ,氧含量对电性有很特别的影响 ,与理想氧含量的样品不同的是 ,氧欠缺样品的电阻出现双峰 ,但是与前者一样仅有一个磁转变 ,这可以用样品中氧含量分布不均匀导致的相分离来解释 ,用这一相分离的图像我们进一步解释了文献中广泛报道的另一个有关Cr掺杂的现象 :与所有锰位掺杂元素相比 。A series of La 0.7 Ca 0.3 Mn 0.92 Cr 0.08 O 3- δ polycrystalline samples with different oxygen content have been prepared by different ways of cooling. It was found that, in contrast to the nearly stoichiometric oxygen-content samples, the oxygen-deficient compounds have double bumps in resistivity with only one magnetic transition. It was explained in terms of electronic and magnetic phase separation due to inhomogeneous distribution of oxygen content in the samples. Moreover, the phase separation picture was used to explain another trait of Cr doping: Cr is less potent in lowering T c , compared with other doping elements.

关 键 词：氧含量 电阻双峰 相分离 锰位掺杂 钙钛矿锰氧化物 铁磁-顺磁转变 金属-绝缘体转变 

分 类 号：O482[理学—固体物理]