Single crystals of the R-type ferrite SrNiRu5O11 were grown from a chloride flux. The hexagonal crystal structure contains ruthenium located on distorted kagome nets. The low-temperature dc magnetic susceptibilities (χ⊥ and χ∥, perpendicular and parallel to the c axis, respectively) diverge as T−0.3, and do not exhibit any indication of long-range magnetic order down to 4.5 K. The electrical resistivity varies as T1.6 below 40 K, which is typical of non-Fermi liquids, and may originate from a competition between residual magnetic interactions among Ni2+ (S = 1) spins and geometrical frustration on the two-dimensional kagome lattice of Ru3+ (S = ½) spins. The transverse magnetoresistivity ρxy at constant temperature T = 5 K for current (J) -magnetic field (H) configurations, J⊥H ∥ c axis and J ∥ H⊥c axis, reveals no anomalous contribution, which is consistent with the absence of magnetic order. Fits of the specific heat data below 10 K require a dominant, but unusual electronic term of the form Cel = γT1.2, which is expected for massless Dirac fermion states in topological insulators, or spin-liquid phases.
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Research at the University of Kentucky was supported by the U.S. Department of Energy Grant No. DE-FG02-97ER45653.
Shlyk, L.; De Long, Lance E.; and Niewa, R., "Structure and Physical Properties of SrNiRu5O11 Single Crystals: An R-Type Ferrite Based on Ordered Kagome Nets" (2017). Physics and Astronomy Faculty Publications. 513.