Double Kondo-lattice-like system in the ytterbium deuterides

Heat capacity measurements on the β-ytterbium deuteride samples with the composition D/Yb=2.71 and 2.46 have been carried out over a temperature range from 1.9 to 260 K. The low temperature specific heat anomalies at around 4 K in YbD2.71 and at 6 K in YbD2.46 are analysed in terms of two different Kondo-lattice systems which, depending on the hydrogen concentration, can be considered in the β-ytterbium deuterides. The specific heat anomaly in YbD2.71 has been analysed as a non-magnetically doped Kondo semiconductor whereas anomaly at about 6 K in YbD2.46 was interpreted as a result of the free carriers vanished owing to the bound electron-hole pairs