Effect of Mn substitution on the thermo-power of the superconductor Mg _1-xMn_xB₂

In this communication a systematic study has been made on the effect of Mn substitution on the thermo-power of MgB₂ superconducting compounds involving 0%, 0.5%, 1.0%, 1.5% and 2% Mn content. The superconducting transition has been found to be very sharp for the pure compound of MgB₂ and it is observed that the transition width increases with Mn content. For small values of Mn content, the thermo-power S(T) increases with Mn content which suggests that the hole density increases. However, with further increase in Mn content, a small decrease in S(T) is observed. For all the compounds, we have observed the expected linear region at low temperatures. There is no systematic trend in the slopes dS/dT with Mn content.