Crystallography, magnetic susceptibility, heat capacity, and electrical resistivity of heavy-fermion Li V2 O4 single crystals grown using a self-flux technique

Magnetically pure spinel compound Li V2 O4 is a rare d -electron heavy fermion. Measurements on single crystals are needed to clarify the mechanism for the heavy-fermion behavior in the pure material. In addition, it is known that small concentrations (<1 mol %) of magnetic defects in the structure strongly affect the properties, and measurements on single crystals containing magnetic defects would help to understand the latter behaviors. Herein, we report flux growth of Li V2 O4 and preliminary measurements to help resolve these questions. The magnetic susceptibility of some as-grown crystals show a Curie-like upturn at low temperatures, showing the presence of magnetic defects within the spinel structure. The magnetic defects could be removed in some of the crystals by annealing them at 700°C. A very high specific heat coefficient γ=450 mJ mol K2 was obtained at a temperature of 1.8 K for a crystal containing a magnetic defect concentration ndefect =0.5 mol %. A crystal with ndefect =0.01 mol % showed a residual resistivity ratio of 50.