Colossal magnetoresistance in the double perovskite oxide La <inf>2</inf>CoMnO<inf>6</inf>

Polycrystalline sample of La2 CoMnO6 has been synthesized by sol-gel technique. The powder x-ray diffraction data confirm the single phase nature of the sample. This compound has monoclinic crystal structure (space group P 21 /n) at room temperature. The temperature dependence of magnetization in low field shows considerable variation between zero-field-cooled and field-cooled magnetization curve below ∼210 K (TC) and it follows Curie-Weiss law in the paramagnetic region. The hysteresis loop at 5 K indicates a coercive field of ∼6kOe and remnant magnetization of ∼2.32 μB /f.u. The temperature dependence of the resistivity data shows semiconductorlike behavior in the temperature range of 5-350 K and follows variable range hopping conduction mechanism in the temperature range 215-350 K. A colossal magnetoresistance of ∼80% is observed at 5 K in an applied field of 80 kOe and MR has a negative sign. © 2010 American Institute of Physics.