Divalent ion substitution effect on Yb-site in Kondo insulator YbB12

Abstract

YbB12 has been investigated energetically as a typical Kondo insulator. To study detailed formation mechanism of Kondo energy gap, we have investigated transport and magnetic properties of Yb1-xR3+xB12 (R3+ = non-magnetic trivalent ions). Recently, we have recently succeeded in substitution of Ca2+ for Yb site in YbB12 by high-pressure synthesis. In Ca- and Lu-substituted alloys both of magnetic susceptibility and specific heat C/T at low temperatures, remarkably show larger increase than those of powdered YbB12. These increases are due to giant increase of density of state in an in-gap state.

Material Development of Kondo Insulator Yb1−xCaxB12 by High-Pressure Synthesis

“…As we have recently succeeded in substitution of Ca 2+ for Yb site in YbB 12 by high-pressure synthesis up to x = 0.2, we report this synthesis condition and the electrical transport properties as a function of x in this paper. As for magnetic properties and specific heat, we have already reported in the other paper [3]. Figure 1 shows the overview of High-pressure (HP) synthesis equipment called MAVO-Press (Max Voggenreiter Corp. in Germany).…”