【摘要】 采用常规的固相合成法分别制备了Fe3+掺杂和2/3Fe3++1/3Fe2+混合Fe离子掺杂的两组Sr14(Cu1-yFey)24O41系列样品.X射线衍射分析显示,当Fe3+离子的掺杂量y≤0.03以及2/3Fe3++1/3Fe2+混合Fe离子掺杂量y≤0.02时,样品呈较纯的单相,并且对于每组样品,随着掺杂离子含量的增加,样品的晶格常数a,b的值逐渐减小.电输运性质的测试分析表明,Fe3+掺杂系列样品中随Fe3+离子含量的增加,样品的电阻率单调减小,揭示了Cu2O3自旋梯子上的空穴载流子浓度增加.进一步分析显示在电阻与温度关系曲线上存在一个渡越温度Tρ,在Tρ上下Sr14(Cu1-yFey)24O41系统存在两种导电机理在Tρ以上,自旋梯子上单个空穴的热激发对电导有贡献;在Tρ以下,一维配对的局域化的空穴跳跃电导起主要作用.2/3Fe3++1/3Fe2+混合Fe离子掺杂样品的输运性质呈现非单调变化的趋势.讨论给出了掺杂引起晶格常数变化与电输运性质变化的关联机理.更多还原

【Abstract】 Two groups of Sr₁₄(Cu_1-yFe_y)₂₄O₄₁ compounds with Fe 3+ doping and 2/3Fe 3+ +1/3Fe 2+ admixture doping respectively were prepared by conventional solid-state reaction. X-ray diffraction analysis shows that the samples have single phase with y≤0.03 of Fe 3+ doping and y≤0.02 of 2/3Fe 3+ +1/3Fe 2+ admixture doping. The lattice parameters a and b decrease gradually when the doping content increases for each group. The measurements of electronic transport properties show that the electrical resistivity decreases monotonically with the increase in y of Fe 3+ doping, which indicates that free hole carriers in the ladder increase. A crossover temperature T-ρ was observed in the Arrhenius plot of the resistivity versus temperature. The decrease of resistivity of the Fe 3+ doped samples is interpreted in term of the dissociation of spin dimers and hole pairs located in the ladder induced by the substitution of Fe 3+ for Cu 2+ .Two kinds of possible conduction mechanisms above and below T-ρ are presented respectively. The fitting of experimental data proves that the conduction mechanism above T-ρ is due to thermal activated single-holes′ contribution, while below T-ρ one-dimensional hopping conduction is dominant.更多还原