Magnetic and structural phase transformations in DyB6 under high pressure

Magnetic and structural phase transitions in the single crystalline DyB6 under high pressure have been studied using the electrical resistivity and the thermal expansion measurements. It is revealed that the Neel temperature, T-N (=25 K), increases below 1 GPa, but tends to saturate above 1 GPa. On the other hand, a sharp change in the linear thermal expansion was observed at T*(=30 Ii) at ambient pressure, which is caused by the Jahn-Teller effect. The transition becomes broader above 1 GPa. These facts suggest that the electronic state of DyB6 in the antiferromagnetic phase is strongly affected by the Jahn-Teller effect under high pressure.