Field-induced Insulator-Metal Transition in EuTe2

We studied in detail the electrical and magnetic properties of the Eu-divalent antiferromagnet EuTe2 with a tetragonal crystal structure using single crystals grown by the Te self-flux method. The observed anisotropic magnetization curves in the antiferromagnetic state below TN = 11.1 K can be understood in terms of the magnetization processes of the twosublattice model of an antiferromagnet with uniaxial magnetic anisotropy. A characteristic feature of this compound is that it becomes an insulator with decreasing temperature at zero magnetic field, but changes to a metal with a relatively low number of carriers in magnetic fields. From the results of magnetization, magnetoresistance, and Hall resistivity measurements in magnetic fields up to mu 0H = 40 T, the insulator-metal transition was found to occur when the magnetization reaches similar to 2 mu B/Eu for both H 11 [110] and [001] at measurement temperatures above 50 K. Energy band calculations revealed that only the up -spin band, which is mainly composed of Te-5p electrons, crosses the Fermi level in the ferromagnetic state, although the energy band possesses a band gap in the paramagnetic and antiferromagnetic states.