Spin glass behavior in LaCo1−xRhxO3 ( x=0.4 , 0.5, and 0.6)

We studied the magnetic ground state of Co/Rh-disordered ${\mathrm{LaCo}}_{1\ensuremath{-}x}{\mathrm{Rh}}_x{\mathrm{O}}₃$ ($x=0.4$, 0.5, and 0.6) by means of powder neutron diffraction (PND), muon spin relaxation ($\ensuremath{\mu}\mathrm{SR}$), ac susceptibility, isothermal magnetic relaxation, and heat capacity measurements. The dc magnetic susceptibility measurements exhibit a cusp around the freezing temperature ${T}_f$ of all studied compounds. PND measurements show no indications of long-range magnetic ordering down to 4 K in all studied samples. $\ensuremath{\mu}\mathrm{SR}$ experiments on these compounds show a peak in the muon spin relaxation rate around ${T}_f$. However, no spontaneous muon spin precession can be observed evidencing the short-range nature of the magnetic ordering. For the $x=0.5$ sample ac susceptibility measurements show that ${T}_f$ shifts to higher temperatures with increasing frequency and becomes suppressed by a dc biasing field. All these observations indicate that the Co/Rh-disordered ${\mathrm{LaCo}}_{1\ensuremath{-}x}{\mathrm{Rh}}_x{\mathrm{O}}₃$ system is a spin glass for $x=0.4$, 0.5, and 0.6.