Evidence for magnetic pseudoscaling in overdoped ${\mathrm{La}}_{2-x}{\mathrm{Sr}}_x{\mathrm{CuO}}_4$

We report the results of electronic Raman-scattering experiments on an overdoped ${\mathrm{La}}_{1.78}{\mathrm{Sr}}_{0.22}{\mathrm{CuO}}_4$ single crystal as a function of temperature. The scattering rate $\Gamma (\overrightarrow{\Omega }0,T)$ has been determined from the normal state $B_{1g}$ spectra in the range $50<~T<~300$ K. $\Gamma \mathrm{}\left(T\right)\mathrm{}$ decreases linearly from 300 K to about 175 K and then undergoes a reduction with respect to the expected mean-field behavior. This trend suggests a crossover to a magnetic pseudoscaling regime at $T_{\mathrm{cr}}\simeq 160$ K. The results are in good agreement with the prediction of the nearly antiferromagnetic Fermi-liquid model. There is no evidence of a pseudogap in the spectra obtained from this overdoped sample.