Complementary Response of Static Spin-Stripe Order and Superconductivity to Nonmagnetic Impurities in Cuprates

We report muon-spin rotation and neutron-scattering experiments on nonmagnetic Zn impurity effects on the static spin-stripe order and superconductivity of the La214 cuprates. Remarkably, it was found that, for samples with hole doping $x\approx 1/8$, the spin-stripe ordering temperature $T_{\mathrm{so}}$ decreases linearly with Zn doping $y$ and disappears at $y\approx 4\%$, demonstrating a high sensitivity of static spin-stripe order to impurities within a ${\mathrm{CuO}}_2$ plane. Moreover, $T_{\mathrm{so}}$ is suppressed by Zn in the same manner as the superconducting transition temperature $T_c$ for samples near optimal hole doping. This surprisingly similar sensitivity suggests that the spin-stripe order is dependent on intertwining with superconducting correlations.

Figure 1

ZF $\mu \mathrm{SR}$ time spectra $A(t)$ for ${\mathrm{La}}_{1.875}{\mathrm{Ba}}_{0.125}{\mathrm{CuO}}_4$ (a) and ${\mathrm{La}}_{1.875}{\mathrm{Ba}}_{0.125}{\mathrm{Cu}}_{0.98}{\mathrm{Zn}}_{0.02}{\mathrm{O}}_4$ (b) recorded at various temperatures. The solid lines represent fits to the data by means of Eq. 3 of Ref. [42].

Figure 2

The temperature dependence of (a) the internal magnetic field $B_{\mu }$ and (c) the magnetic fraction $V_m$ for the polycrystalline samples of ${\mathrm{La}}_{1.875}{\mathrm{Ba}}_{0.125}{\mathrm{Cu}}_{1-y}{\mathrm{Zn}}_y{\mathrm{O}}_4$ ($y=0$, 0.02, 0.04), and (b) the temperature dependence of $B_{\mu }$ for the polycrystalline samples of ${\mathrm{La}}_{1.48}{\mathrm{Nd}}_{0.4}{\mathrm{Sr}}_{0.12}{\mathrm{Cu}}_{1-y}{\mathrm{Zn}}_y{\mathrm{O}}_4$ ($y=0$, 0.01, 0.02, 0.04). The arrows mark the spin-stripe order temperature $T_{\mathrm{so}}$. The solid curves are fits of the data to the power law $B_{\mu }(T)=B_{\mu }(0)[1-(T/T_{\mathrm{so}}{)}^{\gamma }{]}^{\delta }$, where $B_{\mu }(0)$ is the zero-temperature value of $B_{\mu }$. $\gamma$ and $\delta$ are phenomenological exponents.

Figure 3

The normalized static spin-stripe order temperature $T_{\mathrm{so}}/T_{\mathrm{so}}(0)$ for ${\mathrm{La}}_{1.875}{\mathrm{Ba}}_{0.125}{\mathrm{Cu}}_{1-y}{\mathrm{Zn}}_y{\mathrm{O}}_4$ and ${\mathrm{La}}_{1.48}{\mathrm{Nd}}_{0.4}{\mathrm{Sr}}_{0.12}{\mathrm{Cu}}_{1-y}{\mathrm{Zn}}_y{\mathrm{O}}_4$ as a function of Zn content $y$ and the superconducting transition temperature $T_c/T_c(0)$ of ${\mathrm{La}}_{1.85}{\mathrm{Sr}}_{0.15}{\mathrm{Cu}}_{1-y}{\mathrm{Zn}}_y{\mathrm{O}}_4$ as a function of Zn content $y$. The dashed line is a guide to the eye.

Figure 4

(a) $h$ scans through the spin order peak at ($0.5+h$,0.5,0) for the single crystals of ${\mathrm{La}}_{1.48}{\mathrm{Nd}}_{0.4}{\mathrm{Sr}}_{0.12}{\mathrm{Cu}}_{1-y}{\mathrm{Zn}}_y{\mathrm{O}}_4$ ($y=0$, 0.016), recorded at the base temperature $T=1.75\mathrm{K}$. The intensities have been normalized to the crystal volume in the neutron beam. The solid lines represent the Gaussian fits to the data. (b) Peak intensity versus temperature of the ($0.5+h$, 0.5, 0) spin order peak, normalized to the crystal volume in the neutron beam.

Figure 5

(a) Temperature dependence of the magnetic volume fraction $V_m$ for ${\mathrm{La}}_{1.845}{\mathrm{Ba}}_{0.155}{\mathrm{Cu}}_{1-y}{\mathrm{Zn}}_y{\mathrm{O}}_4$ ($y=0$, 0.02, 0.04). (b) The normalized static spin-stripe order temperature $T_{\mathrm{so}}/T_{\mathrm{so}}(0)$ and the normalized superconducting transition temperature $T_{\mathrm{c}}/T_{\mathrm{c}}(0)$ for ${\mathrm{La}}_{1.845}{\mathrm{Ba}}_{0.155}{\mathrm{Cu}}_{1-y}{\mathrm{Zn}}_y{\mathrm{O}}_4$ as a function of Zn content $y$. The dashed line is a guide to the eye.