Anomalous Hall Effect in Calcium -Doped Lanthanum Cobaltite and Gadolinium

92 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2003.The Hall resistivity, magnetoresistance, and magnetization of a Gadolinium single crystal were measured in fields up to 30 T. Cobaltite films were grown via laser ablation and characterized by a variety of techniques. Hall resistivity, magnetoresistance, magnetization, and magnetothermopower of L 1-xCaxCoO3 samples with 0.15 < x < 0.4 were measured in fields up to 7 T. The Gd results suggest that Berry's phase contributes partially to the Hall effect near TC. Berry's phase theories hold promise for explaining the large anomalous Hall effect in La1-xCaxCoO3 near T C, but the material presents many additional complexities, including a unique low temperature magnetoresistance. At low temperature, the Hall effect may be best explained by spin-polarized carriers scattering off of orbital disorder in spin-ordered clusters.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD