Low-temperature properties of pyrochlore Lu2Ir2O7

•A bifurcation of ZFC and FC magnetization data is observed below 140 K.•It mirrors as a broad anomaly in the temperature development of specific heat.•Short-range correlations between Ir magnetic moments, rather than long-range order of Ir sublattice.•A strong frequency dependence of ac-susceptibility, a paradigmatic sign of a spin-glass transition.•Relatively weak electron-phonon interaction and semimetallic ground state in Lu2Ir2O7, supported by DFT calculations. Low-temperature properties of Lu2Ir2O7 were studied by means of magnetization, ac-susceptibility and specific heat measurements. Our low-temperature measurements reveal a bifurcation of ZFC and FC magnetization data below 140 K, which is further pronounced as a broad anomaly in the temperature development of specific heat and ac-susceptibility. The anomaly can be attributed to the same physical mechanism as discussed for other A2Ir2O7 with A = magnetic rare-earth element, i.e. to short-range correlations among Ir4+ magnetic moments, rather than to a long-range order of Ir sublattice reported earlier. The ac-susceptibility data revealed a strong frequency dependence of the signal, a paradigmatic sign of a spin-glass transition. The analysis of low-temperature specific heat data brought important information on physical properties of Lu2Ir2O7, in striking agreement with our density functional theoretical (DFT) calculations, concluding relatively weak electron-phonon interaction and semimetallic ground state in Lu2Ir2O7.