2018/07/11 by Ashiwini Balodhi, Yogesh Singh, Balodhi, Ashiwini +1
Physics and Astronomy · Mathematics · #Advanced Condensed Matter Physics #Algebraic structures and combinatorial models #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.1807.03940
We report on the effects of introducing magnetic and non-magnetic disorder in the hyperkagome iridate quantum spin liquid (QSL) candidate Na4Ir3O8 by partially replacing Ir4+ (S = 1/2) with Ru4+ (S = 1) or Ti4+ (S = 0). Specifically, we synthesized Na4(Ir1-xRux)3O8 (x = 0.05, 0.10, 0.2, 0.3) and Na4Ir2.7Ti0.3O8 samples and measured electrical transport, AC and DC magnetization, and heat capacity down to T = 1.8 K. Na4Ir3O8 is associated with a large Weiss temperature θ= -650 K, a broad anomaly in magnetic heat capacity Cmag at T ≈25 K, low temperature power-law heat capacity, and spin glass freezing below Tf ≈ 6 K. We track the change in these characteristic features as Ir is partially substituted by Ru or Ti. We find that for Ru substitution, θ increases and stays negative, the anomaly in Cmag is suppressed in magnitude and pushed to lower temperatures, low temperature C ∼ Tα with α between 2 and 3 and decreasing towards 2 with increasing x, and Tf increases with increase in Ru concentration x. For Ti substitution we find that θ and Tf become smaller and the anomaly in Cmag is completely suppressed. In addition, introducing non-magnetic Ti leads to the creation of orphan spins which show up in the low temperature magnetic susceptibility.