Electrical transport properties of EuTe under high pressure

The pressure-induced electronic and optical properties of EuTe were investigated up to 35.6 GPa. Using first-principles calculations, it was found that EuTe undergoes a pressure-induced NaCl-CsCl structural transition above 13 GPa. The metallic character of EuTe is strengthened with an increase in pressure, according to the calculation results of band structure and electron density of states. EuTe is observed to undergo semiconductor-to-semimetal transition when the Fermi surface is crossed only by the spin-up band at 6 GPa, and the metallization transition is shown at 13 GPa. The structural phase transition of EuTe is reflected at approximately 13.8 GPa based on the discontinuous electrical parameters, and the abrupt decrease of resistivity is caused by a joint increase in the carrier concentration and mobility, while the abrupt decrease of Hall coefficient is attributed to the increase of carrier concentration. The metallization transition is also evidenced at 13.8 GPa by temperature-dependent resistivity. The discontinuous changes in the optical parameters at around 6.9 GPa and 13.8 GPa are caused by semiconductor-to-semimetal transition and structural phase transition, respectively. The transition pressure is reduced in the presence of light, occurring at approximately 12.7 GPa.