We study the effect of non-magnetic Zn$^{2+}$ (spin-$0$) and magnetic Ni$^{2+}$ (spin-$1$) impurities on the ground state and low-lying excitations of the quasi-one-dimensional spin-$1/2$ Heisenberg antiferromagnet Sr$_{2}$CuO$_{3}$ using inelastic neutron scattering, specific heat and bulk magnetization measurements. We show that 1 \% Ni$^{2+}$ doping in Sr$_2$CuO$_3$ results in a sizable spin gap in the spinon excitations, analogous to the case of Ni-doped SrCuO$_2$ previously reported [ref. 1]. However, a similar level of Zn$^{2+}$ doping in SrCuO$_2$, investigated here for comparison, did not reveal any signs of a spin gap. Magnetic ordering temperature was found to be suppressed in the presence of both Zn$^{2+}$ and Ni$^{2+}$ impurities, however, the rate of suppression due to Ni$^{2+}$ was found to be much more pronounced than for Zn$^{2+}$. Effect of magnetic field on the ordering temperature is investigated. We found that with increasing magnetic field, not only the magnetic ordering temperature gradually increases but the size of specific heat anomaly associated with the magnetic ordering also progressively enhances, which can be qualitatively understood as due to the field induced suppression of quantum fluctuations.
Finite-size effects in the quasi-one-dimensional quantum magnets Sr$_{2}$CuO$_{3}$, Sr$_{2}$Cu$_{0.99}$M$_{0.01}$O$_{3}$ (M = Ni, Zn), and SrCuO$_{2}$
研究了准一维自旋S = $\frac{1}{2}$海森堡反铁磁体Sr $_{2}$ CuO $_{3}$，Sr $_{2}$ Cu $_{0.99}$ M $_{0.01}$ O $_{3}$（M = Zn和Ni）和SrCuO $_{2}$的磁性的有限尺寸效应.磁化率数据进行了分析，以估计浓度的链断裂由于extraminated缺陷和/或由于轻微的氧非化学计量。我们发现，Sr $_{2}$ Cu $_{0.99}$ Ni $_{0.01}$ O $_{3}$的磁化率可以通过考虑Ni $^{2+}$作为一个标量缺陷（$S_{eff}=0$），表明Ni自旋被屏蔽。在Sr $_{2}$ Cu $_{0.99}$ Zn $_{0.01}$ O $_{3}$磁化率分析产生的缺陷浓度小于标称值，这是在良好的定性与晶体生长实验。研究了掺杂对低温长程自旋有序态的影响。在化合物SrCuO $_{2}$中，由Z字形S = $\frac{1}{2}$链组成，讨论了自旋阻挫对磁有序和由磁化率数据确定的缺陷浓度的影响。
Crystal growth of the non-magnetic Zn$^{2+}$ and magnetic Co$^{2+}$ doped quasi one-dimensional spin chain compound SrCuO$_{2}$ using the travelling solvent floating zone method
Anisotropic microwave conductivity of cuprate superconductors in the presence of CuO chain induced impurities
在动能驱动的超导机制下，研究了邻位Ⅱ型$_2$的微波电导各向异性.邻位-Ⅱ $_2$ $_3$ O $_{6.50}$的特征在于填充和空$\hat{b}$轴CuO链的周期性交替。考虑CuO链诱导的扩展各向异性杂质散射，基于准粒子激发和散射过程的节块近似，再现了邻位Ⅱ型$_2$微波电导各向异性的主要特征，包括$\hat{a}$轴和$\hat{b}$轴微波电导的能量和温度依赖性的强度和线形.我们的研究结果也证实了$\hat{b}$轴CuO链诱导杂质是各向异性的主要来源。
Incommensurate magnetic order and dynamics induced by spinless impurities in YBa$_2$Cu$_3$O$_{6.6}$
我们报道了一个非弹性中子散射和μ子自旋弛豫研究的影响，2%的无自旋（Zn）杂质的磁性秩序和动力学的YBa $_2$铜$_3$ O $_{6.6}$，欠掺杂的高温超导体，在其正常状态下表现出突出的自旋赝能隙。Zn取代诱导静态磁秩序在低温下，并触发一个大规模的光谱重量重新分配的磁共振模式在38毫电子伏到单轴，不相称的自旋激发的能量远低于自旋赝能隙。这些观测结果表明，在量子临界点附近，无公度磁序和超导性之间存在着竞争。与La $_{2-x}$ Sr $_x$ CuO $_{4}$的先前数据的比较表明，这种行为对于层状铜氧化物是普遍的，并且类似于一维量子磁体中的杂质诱导的磁序。
Sign reversal of the Hall resistance in the mixed-state of La$_{1.89}$ Ce$_{0.11}$CuO$_{4}$ and La$_{1.89}$Ce$_{0.11}$(Cu$_{0.99}$Co$_{0.01}$)O$_{4} $ thin films
研究了LaPDMATHABMM Ce $_{0.11}$ CuO $_{4}$（LCCO）和$_{1.89}$ Ce $_{0.11}$（Cu $_{0.99}$ Co $_{0.01}$）O $_{4}$（LCCO：Co）超导薄膜的输运性质。当外场$\bf H$沿晶体学c轴方向施加时，在LCCO：Co薄膜的混合态中观察到霍尔电压的双符号反转，而在LCCO中检测到霍尔电压的单符号反转。在LCCO中，如果磁场倾斜离开膜平面，则可以恢复霍尔信号的双符号反转。我们发现，从一个到两个霍尔符号反转的转变与钉扎从强到弱的变化相一致。这种温度/场诱导的转变是由LCCO：Co中的磁性杂质或由LCCO中的饼状涡旋和面内约瑟夫森涡旋之间的耦合引起的。这些结果与早期的理论和数值预测一致。
Random Fields from Quenched Disorder in an Archetype for Correlated Electrons: the Parallel Spin Stripe Phase of La$_{1.6-x}$Nd$_{0.4}$Sr$_x$CuO$_4$ at the 1/8 Anomaly
