The c-axis oriented thin films were synthesized on (1¯1▪2) Al2O3 substrates by using a pulsed laser deposition technique and the longitudinal and the Hall resistivities were measured in the ab-plane direction. The as-grown thin films had a TC of 39.2K with a sharp transition width of ~0.15K. In the normal state, the Hall coefficient (RH) behaves as RH ~ T with increasing temperature up to 130K and then deviates from that linear T-dependence at higher temperatures. The T2 dependence of the cotangent of the Hall angle was only observed above 130K. The absolute value of the hole density was estimated to be some 2 orders of magnitude higher than that of YBa2Cu3O7.

Synthesis of c-Axis-Oriented MgB2 Thin Films and the Hall Effect. W.N.Kang, H.J.Kim, H.J.Kim, E.M.Choi, K.H.P.Kim, H.S.Lee, S.I.Lee: Superconductor Science and Technology, 2003, 16, 237-40