Elastic properties and phase diagram of the rare-earth monopnictide TbSb

We have investigated the magnetic and elastic properties of rare-earth monopnictide TbSb by means of specific heat, high-field magnetization, and ultrasonic measurements. A pronounced anomaly was observed in the specific heat and elastic constants at an antiferromagnetic transition of T-N=15.5 K. A pronounced softening towards low temperatures in (C-11-C-12)/2 and C-44 suggests that a degree of orbital freedom plays an important role at low temperatures. Furthermore, the high-field magnetization measurement exhibits an unexpected metamagnetic transition: clear three sharp steps. This was observed only for H//<111>, while only one step was observed for H//<100> and <110>. The established (H-T) phase diagram from the present experimental results consists of mainly four phases. The obtained (H-T) phase diagram is discussed in terms of magnetic and quadrupolar interactions.