Magnetic field dependence of low-temperature specific heat of the spinel oxide superconductor LiTi₂O₄

Magnetic field dependence of low temperature specific heat of spinel oxide superconductor LiTi₂O₄ has been elaborately investigated. In the normal state, the obtained electronic coefficient of specific heat γ_n = 19.15 mJ/mol K², the Debye temperature Θ_D=657 K and some other parameters are compared with those reported earlier. The superconducting transition at T_c∼11.4 K is very sharp (ΔT_c∼0.3 K) and the estimated δC/γ_nT_c is ∼1.78. In the superconducting state, the best fit of data leads to the electronic specific heat C _es/γ_nT_c=9.87 exp(-1.58 T_c/T) without field and γ(H) ∝ H^0.95 with fields. In addition, H_c2(0)∼11.7 T, H_c(0)∼0.32 T, ξ_GL(0) ∼55 Å, λ_GL(0)∼1600 Å, and H _c1(0)∼26 mT are estimated from the Werthamer-Helfand-Hohenberg (WHH) theory or other relevant relations. All results from the present study indicate that LiTi₂O₄ can be well described by a typical type-II, BCS-like, moderate coupling, and fully gapped superconductor in the dirty limit. It is further suggested that LiTi₂O₄ is a moderately electron-electron correlated system.