Freezing of Anisotropic Spin Clusters in ${\mathrm{La}}_{1.98}{\mathrm{Sr}}_{0.02}{\mathrm{CuO}}_{4}$

A spin-glass compound, La1.98Sr0.02CuO4, shows quasi-three-dimensional magnetic ordering below $\sim$40K. A remarkable feature is that the magnetic correlation length along the orthorhombic aortho axis is much longer than that along the bortho axis, suggesting that the spin structure is closely related to the diagonal stripe structure. The spin-glass state can be expressed as a random freezing of quasi-three-dimensional spin clusters with anisotropic spin correlations ($\xi′$a$\sim$160\AA, $\xi′$b$\sim$25\AA, and $\xi′$c$\sim$4.7\AA{} at 1.6 K). The new magnetic state is important as an intermediate phase between the three-dimensional antiferromagnetic ordered phase in La2CuO4 and the incommensurate phase in La1.95Sr0.05CuO4 in which the positions of the incommensurate peaks are rotated by 45$^i̧rc$ in reciprocal space about ($\pi$,$\pi$) from those observed in the superconducting La2CuO4 compounds.     «

A spin-glass compound, La1.98Sr0.02CuO4, shows quasi-three-dimensional magnetic ordering below $\sim$40K. A remarkable feature is that the magnetic correlation length along the orthorhombic aortho axis is much longer than that along the bortho axis, suggesting that the spin structure is closely related to the diagonal stripe structure. The spin-glass state can be expressed as a random freezing of quasi-three-dimensional spin clusters with anisotropic spin correlations ($\xi′$a$\sim$160\AA, $\xi′...     »