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ELECTRONIC AND MAGNETIC PHASE TRANSITIONS IN QUASI - ONE-DIMENSIONAL AND THREE-DIMENSIONAL METALLIC COMPOUNDS (CHALCOGENIDE, TRANSITION METAL)
Abstract
Electronically driven structural and magnetic transitions have been studied in several new compounds. The compounds are either quasi-one-dimensional chalcogenide conductors or three dimensional transition metal compounds. The linear chain compound Mo(,2)S(,3) has resistivity and susceptibility anomalies with considerable hysteresis. These structural transitions may be due to charge density waves. The introduction of nickel impurities into TaS(,3) has the effect of smearing the charge density wave transition which occurs in TaS(,3). These Ni-doped compounds show non-ohmic behavior at high electric fields, presumably associated with depinning of charge density waves. Fe(,0.01)Ta(,0.92)Se(,4) and Nb(,1.09)Se(,4) undergo charge-density-wave transitions at 250 and 300K, respectively. Non-ohmic conductivity is observed in both compounds below the transition temperature. Fe(,0.01)Ta(,1.06)Se(,4) shows semi-conducting behavior below room temperature. TaSe(,3), Nb(,2)Se(,3) and Nb(,3)S(,4) are metallic down to 4.2K, with no evidence of phase transitions. The intrinsic resistivity has a temperature dependence of the form T('n) (2 (LESSTHEQ) n (LESSTHEQ) 3) in the low temperature region. This behavior is consistent with the theory of Oshiyama et al., which is based on electron-electron Umklapp processes. The magnetic properties of several three-dimensional compounds of the form TPd(,3) and TNi(,3), where T is a 3d or 4d transition metal, have been investigated. Some compounds of this class have been predicted to be itinerant ferromagnets by recent self-consistent spin-polarized band calculations of Moruzzi and Williams. Magnetic susceptibility measurements on MoPd(,3), CrNi(,3) and VNi(,3) down to 4.2K do not show any evidence of magnetic ordering. Results on these compounds are compared with paramagnetic density-of-states calculations of Jaswal and of Moruzzi and Williams. The MnPd(,3) and CrPd(,3) samples are disordered and magnetic susceptibility and high-field magnetization measurements show that both undergo spin-glass transitions around 40K. These results are discussed in terms of a clustering model.
Subject Area
Condensation
Recommended Citation
RASHID, HARUNOR MD., "ELECTRONIC AND MAGNETIC PHASE TRANSITIONS IN QUASI - ONE-DIMENSIONAL AND THREE-DIMENSIONAL METALLIC COMPOUNDS (CHALCOGENIDE, TRANSITION METAL)" (1983). ETD collection for University of Nebraska-Lincoln. AAI8404844.
https://digitalcommons.unl.edu/dissertations/AAI8404844