Magnetic phase diagram of Ca2+xY 2-xCu5O10-delta : Oxygen hole-doping effects
by Park, Keeseong, Ph.D., THE UNIVERSITY OF TEXAS AT AUSTIN, 2007, 150 pages; 3277583

Abstract:

Oxygen hole-doping e ects on a spin-chain system, Ca 2+xY2-xCu 5O10-δ(CaYCuO) are reported. CaYCuO is a good specimen to study the magnetic properties of the CuO2 chain at the ground state because it has no complex structure other than the chain and it has hole dopability up to the formal copper valence number of +2.4. Specically, we can dope holes into the CuO2 chain by substituting Ca 2+ for Y3+ or by utilizing oxygen deciency. After a systematic study of the two methods to dope holes, we found that oxygen doping makes a more critical change in magnetic ordering in the chain than the replacement of Ca2+. Oxygen deciency effects of the chain on the magnetic properties were explained using a mean field theory. A new relation for the effective hole doping was found as p = x – aδ, where a = 3/2( x – δ) – 1/4. We study the anisotropy of magnetic properties of single crystal Li-cathode material (LiFePO4) for g-factor, Curie-Weiss temperature, and effective moment. Magnetic properties Au/SiO2 coated γ-Fe2O3 are compared with pure γ-Fe2O3 finding a decrease in the blocking temperature and the irreversible temperature for the coated nanoparticles.

 
AdviserJohn T. Markert
SchoolTHE UNIVERSITY OF TEXAS AT AUSTIN
SourceDAI/B 68-08, p. , Dec 2007
Source TypeDissertation
SubjectsCondensed matter physics
Publication Number3277583
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