Flux Growth of Heavy Fermion LiV$_2$O$_4$ Single Crystals

The spinel-structure compound ${\rm LiV_2O_4}$ is a rare $d$- electron heavy fermion. Measurements on single crystals are needed to clarify the mechanism for the heavy fermion behavior. 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 growth at 950--1030~$^\circ$C of 1~mm$^3$ size octahedron-shaped ${\rm LiV_2O_4}$ single crystals using a self- flux technique. The magnetic susceptibility of the as-grown crystals shows a Curie-like upturn at low temperatures arising from $\approx 0.5$ mol\% magnetic defects within the spinel structure. After annealing at 700~$^\circ$C, the Curie-like upturn (and magnetic defects) disappeared in some crystals, thus revealing the known intrinsic nearly temperature-independent behavior below $\sim 20$~K\@. Preliminary heat capacity measurements on as-grown crystals containing magnetic defects showed a high linear specific heat coefficient $\gamma$ = 450 mJ/ (mole K${^2}$) at 1.8~K\@. Additional electronic tranport, magnetic and thermal measurements on both as-grown and annealed crystals will be presented.