Muon spin relaxation study of the stripe phase order inLa1.6−xNd0.4SrxCuO4and related 214 cuprates

Abstract

We present zero-field muon spin relaxation (\ensuremath{\mu}SR) measurements of ${\mathrm{La}}_{1.6\ensuremath{-}x}{\mathrm{Nd}}_{0.4}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ with $x=0.125,0.15,0.2;{\mathrm{La}}_{1.475}{\mathrm{Nd}}_{0.4}{\mathrm{Ba}}_{0.125}{\mathrm{CuO}}_{4},{\mathrm{La}}_{1.875}{\mathrm{Ba}}_{0.125}{\mathrm{CuO}}_{4},$ and ${\mathrm{La}}_{1.875}{\mathrm{Ba}}_{0.125\ensuremath{-}y}{\mathrm{Sr}}_{y}{\mathrm{CuO}}_{4}$ with $y=0.025,0.065.$ All of the samples with dopant concentrations $x+yl~0.15$ show similar static magnetic order with coherent precession of the muon spins below ${T}_{N}\ensuremath{\approx}30\mathrm{K},$ with a $\stackrel{\ensuremath{\rightarrow}}{T}0$ ordered Cu moment $\ensuremath{\approx}0.3{\ensuremath{\mu}}_{B}.$ The samples with $x=0.20$ show no coherent precession but manifest two distinct relaxation regimes, typical of quasistatic magnetism. We then present transverse-field \ensuremath{\mu}SR hysteresis measurements of the ${\mathrm{La}}_{1.45}{\mathrm{Nd}}_{0.4}{\mathrm{Sr}}_{0.15}{\mathrm{CuO}}_{4}$ and ${\mathrm{La}}_{1.4}{\mathrm{Nd}}_{0.4}{\mathrm{Sr}}_{0.2}{\mathrm{CuO}}_{4}$ systems that show a large superconducting response below approximately 7 K and 12 K, respectively. We argue that superconductivity and magnetic order coexist in the $x=0.15$ system.