Thermopower of pure bismuth wires in high magnetic fields

E. Condrea¹, A.D.Grozav¹, A.G.M. Jansen², I. Sheikin²

¹Instituteof Applied Physics, Academiei 5, MD-2028 Chisinau, Republic of Moldova

²Grenoble HighMagnetic Field Laboratory, Max-Planck-Institute fur Festkorperforshung andCentre National de la Recherche Scientifique, B.P. 166, F-38042 Grenoble Cedex09, France

The thermopower (TEP), S, of cylindrical Bi wires with diameters d =200 ± 50 nm and 1300 ± 200 nm has been measured in the temperature range 5 – 25 Kand in magnetic fields up to 20 T. In these experimental conditions, all ourwire samples show positive thermopower, however, the variation of zero-fieldTEP with temperature is significantly different for samples with differentdiameters. For the 200-nm samples, the magnitude of S(0,T) increases from about0.035 mV/K at T = 5.4 K to about 0.11 mV/K at T = 25.6 K, in contrast to thethick wires which have dS/dT < 0 and smaller TEP values.

In good single crystalline Bi wires, we have detected the well-definedquantum oscillations of magnetothermopower, which are periodic in 1/B and canbe seen even at T = 25 K. The frequencies of these oscillations do not dependon T. An anomalous increase in the oscillation amplitude with increasingtemperature was observed.

A portion of this work wasperformed at the National High Magnetic Field Laboratory (Tallahassee), whichwas supported by the NIS Visitors Program. Partial support came from theMRDA/CRDF Award No. MP2-3046.