Magnetotransport and Fermi-surface modification in NbSe(sub 3)

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6109843

Everson, M P

A detailed study has been made of the magnetoresistance in the charge-density wave material NbSe{sub 3}. The magnetoquantum oscillations in NbSe{sub 3} exhibit frequency shifts and beat structures due to an interaction between the normal Fermi surface and the local CDW pinning configuration. The large quantum oscillations in magnetoresistance are attributed to the presence of a magnetic breakdown network in which open orbits in k-space are connected by magnetic breakdown to a small pocket of carriers. The size of the pocket is modified due to local variation in the CDW pinning configuration. After CDW depinning has occurred frequency shifts and loss of beat structure are observed due to changes in the exact CDW pinning configuration. A model consisting of a one-d open-orbit breakdown network with a distribution of sizes for the small pockets has produced good fits to the data. The MB network model provides a mechanism for coupling magnetoresistance to the CDW configuration, which can be modified by electric and magnetic fields. The NbSe{sub 3} resistive anomaly below T = 59K was found to be greatly enhanced by application of transverse magnetic fields in the range 10-230kG. The resistance anomaly enhancement is essentially eliminated in the high-E limit of CDW depinning, leaving almost no magnetoresistance. For H longitudinal there is no enhancement of the resistive anomaly. These results are consistent with H-induced changes in normal carrier densities and mobilities. A model in which a magnetic field transverse to the high-conductivity axis in a density-wave material induces more perfect nesting in the DW can explain the above results.

• Research Organization: Virginia Univ., Charlottesville, VA (USA)
• OSTI ID: 6109843
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
CARRIER DENSITY
CARRIER MOBILITY
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY LEVELS
FERMI LEVEL
HALL EFFECT
INTERMETALLIC COMPOUNDS
MAGNETIC FIELDS
MAGNETIC FLUX
MAGNETORESISTANCE
MOBILITY
MODIFICATIONS
NIOBIUM ALLOYS
PHYSICAL PROPERTIES
SELENIUM ALLOYS