High-temperature oscillations of bismuth conductivity in the ultra-quantum limit

The results of joint studies of Shubnikov-de Haas oscillations and "high-temperature" oscillations (HTO) of diagonal and nondiagonal components of the magnetoresistance tensor for pure bismuth in magnetic fields up to 20 T are presented. The oscillations are measured for magnetic field directions close to trigonal and binary crystallographic axes at temperatures 4-43 K. A comparison of the variation of energy spectrum parameters for bismuth in ultra-quantum limit with peculiarities of "high-temperature" oscillations leads to the conclusion confirming the correspondence between HTO periods to the width of the energy band overlapping region. In the case when light electrons in two ellipsoids are in the ultra-quantum limit, a correlation between the exit of the last Landau level of heavy electrons (i.e., complete closure of the third electron ellipsoid) and the vanishing of HTO periods is observed in high magnetic fields. This experimental fact can play a key role in the theoretical description of the nature of HTO. (C) 1999 American Institute of Physics.