Measurements of elastic anomalies in charge-density-wave conductors

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

OSTI ID:6069345

Xiang, Xiaodong

For the last two decades, extensive studies have been done to understand the underlying physics of charge-density-wave (CDW) conductors. The most interesting phenomenon is the collective electron conduction process analogous to that in superconductors. While the anomalous transport properties associated with the CDW phase transition and its dynamics have been relatively well studied, the elastic anomalies are poorly understood. My research motivation was to further study the latter by extending the elastic measurements to different materials, different elastic moduli, and most importantly, to a wider frequency range. Two types of elastic anomalies are associated with the CDW: (a) the transition anomaly, which is associated with the formation of the CDW around and below the CDW phase transition temperature {Tc}, and (b) the depinning anomaly, which is associated with the depinning of the CDW condensate from impurities when the applied electric field exceeds a threshold field (E > ET). Using a dc vibrating reed technique, the author had studied the transition anomalies in Young's modulus (Y) of ZrTe{sub 3} and Nb{sub 3}Te{sub 4} and both anomalies in the shear modulus (G) and Y of TaS{sub 3} and NbSe{sub 3}. Unexpectedly large depinning anomalies in G (larger than those in Y) have been observed for both TaS{sub 3} and NbSe{sub 3}. In order to study the frequency dependence of the anomalies, he has developed an rf helical resonator detector to improve the sensitivity of the vibrating reed technique. The theoretical analysis of the sensitivity for such an rf resonator detector has been conducted and the result shows that the limiting sensitivity is much higher than that of lumped LC circuit or dc detectors. With the new apparatus, many resonant overtones of the sample can be detected and therefore, elastic measurements can be performed in much a wider frequency range.

• Research Organization: Kentucky Univ., Lexington, KY (USA)
• OSTI ID: 6069345
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
CHALCOGENIDES
CHARGE DENSITY
ELASTICITY
ELECTRIC CONDUCTORS
ELECTRIC FIELDS
ELEMENTS
FREQUENCY DEPENDENCE
IMPURITIES
MEASURING METHODS
MECHANICAL PROPERTIES
METALS
NIOBIUM COMPOUNDS
NIOBIUM SELENIDES
NIOBIUM TELLURIDES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
REFRACTORY METAL COMPOUNDS
RESEARCH PROGRAMS
SELENIDES
SELENIUM COMPOUNDS
SHEAR
SULFIDES
SULFUR COMPOUNDS
TANTALUM COMPOUNDS
TANTALUM SULFIDES
TELLURIDES
TELLURIUM COMPOUNDS
TENSILE PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TRANSITION TEMPERATURE
YOUNG MODULUS
YTTRIUM
ZIRCONIUM COMPOUNDS
ZIRCONIUM TELLURIDES