Identification of a Griffiths-like phase and its evolution in the substituted pyrochlore iridates Y2Ir2−xCrxO7 (x=0.0,0.05,0.1,0.2)

We report the Griffiths phase (GP)-like state along with a cluster-glass-like state in geometrically frustrated antiferromagnetic Cr-substituted ${\text{Y}}₂{\text{Ir}}₂{\text{O}}₇$ pyrochlore iridates. The strength of the GP-like behavior increases with substitution. Interestingly, isothermal remanent magnetization suggests the Ising-like interaction of spins in the GP region. The GP-like state is not attributed to the structural disorder as substitution of Cr does not induce any structural change. Then the spin coupling between ${\text{Cr}}³⁺\ensuremath{\leftrightarrow}{\text{Cr}}³⁺$, ${\text{Ir}}⁴⁺\ensuremath{\leftrightarrow}{\text{Ir}}⁴⁺$, ${\text{Ir}}⁴⁺\ensuremath{\leftrightarrow}{\text{Cr}}³⁺$, and ${\text{Ir}}⁴⁺\ensuremath{\leftrightarrow}{\text{Ir}}⁵⁺$ leads to the competition between antiferromagnetic and ferromagnetic correlations. It gives rise to Ruderman-Kittel-Kasuya-Yosida (RKKY)-like interaction between ${\text{Cr}}³⁺$ local magnetic moments mediated by itinerant Ir conduction electrons, hence, as a result, GP and cluster-glass-like states emerge.