EVIDENCE FOR LIGHT AND HEAVY CONDUCTION ELECTRONS AT THE ZONE CENTER IN KTAO3

The Shubnikov-de Haas oscillation of the magnetoresistance was observed for the n-type KTaO3 in the magnetic field up to 105 kOe at liquid-helium temperatures. Angular variation of the extremal areas of the Fermi surface supports the zone-center-warped-band model, and rules out the many-valley model. However, contrary to the theoretical expectation, the 100 bulges of the warped Fermi surface of the heavy electron are found to be absent or strongly depressed by some unknown mechanism. © 1979 The American Physical Society.