Temperature and Magnetic Field Dependence of the Conductivity of EuO

The conductivity of EuO has been measured as a function of temperature from 30 to 300°K in magnetic fields up to 50 kG. The zero-field resistivity exhibits a sharp elbow at about 50°K, and increases as much as 10
⁸
between 50 and 70°K to a broad maximum between 75 and 80°K. In an applied magnetic field, the broad maximum is rapidly decreased and the elbow is shifted to higher temperatures. These data are interpreted in terms of a transfer of electrons between a conduction band and an electron trap. In the model the energy separation between the band and trap level depends on the magnetic energy of the crystal and is thus a strong function of temperature and magnetic field. At low temperatures the trap level is assumed to be above the conduction band edge such that the electrons lie in the band. As the temperature is increased the energy of the band edge increases such that it crosses the trap level at about 50°K. The large increase in resistivity with increasing temperature and the effects due to the magnetic field are explained by the transfer of electrons from the energy band into the trap states.