Quasi-local critical nature of cooperative paramagnetic fluctuations in CaRuO₃ metal

We report new observation of cooperative paramagnetic fluctuations of Ru$^{4+}$ spins that coexist with the non-Fermi liquid state in CaRuO$_{3}$ perovskite below T $\simeq$ 22 K. Detailed electrical, magnetic and neutron scattering measurements reveal that the Ru$^{4+}$ ions reside in magnetic field independent random domains with dynamic properties that are reminiscent of the cooperative paramagnetic fluctuations. The linear ($E/T$) scaling of the dynamic susceptibilities and divergence of the mean relaxation time as $T$$\rightarrow$~0 K suggest quasi-local critical nature of the spin fluctuations. We argue that the non-Fermi liquid behavior arises due to the quantum critical nature of the cooperative paramagnetic fluctuations in CaRuO$_{3}$