Optical conductivity and penetration depth in MgB2 - art. no. 097003

The complex conductivity of a MgB2 film has been investigated in the freque ncy range 4 < v < 30 cm(-1) and for temperatures 2.7 < T < 300 K. The overa ll temperature dependence of both components of the complex conductivity is reminiscent of BCS-type behavior, although a detailed analysis reveals a n umber of discrepancies. A peak in the temperature dependence of the real pa rt of the conductivity is detected for frequencies below 9 cm(-1). The supe rconducting penetration depth follows a T-2 behavior at low temperatures.