La_((1+x)/3)Ba_((2-x)/3)Mn_(x)Cu_(1-x)O_(3)(0.8≤x≤1)晶体结构和输运性质

Lattice Structure and Transport Properties of the System La_((1+x)/3)Ba_((2-x)/3)Mn_(x)Cu_(1-x)O_(3)(0.8≤x≤1)

用固态反应法制备了名义组分为 L a(1 + x) /3Ba(2 - x) /3Mnx Cu1 - x O3(0 .8≤ x≤ 1) 的系列试样。试样结构的单相性经粉末 X射线衍射分析而得以证实 ,且随 Cu的掺杂其结构由未掺杂时的立方对称性转变为正交对称性。输运实验表明 :所有试样均经历了半导体到金属的转变 ,但转变温度 TP随掺杂量增加而逐渐移向低温端 ;外加磁场大大增加了 TP附近的导电性 ,导致

Single phase La (1+ x )/3 Ba (2- x )/3 Mn x Cu 1- x O 3(0 8≤ x ≤1) samples were prepared by solid state reaction. Upon doping with Cu, the lattice structure changes from cubic to orthorhombic. Transport properties measurements show that all samples experience a metal insulator transition, and that the transition temperature (T c ) decreases in response to doping. Application of a magnetic field greatly increases the conductivity, and leads to a maximum magnetoresistance near T c .