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Title: Colossal electroresistance, magnetoimpedance, and magnetocaloric effects in selected manganites
Keywords: electroresistance, magnetoimpedance, magnetocaloric, magnetoresistance, phase separation, manganites
Issue Date: 2-Jun-2010
Citation: ALWYN REBELLO (2010-06-02). Colossal electroresistance, magnetoimpedance, and magnetocaloric effects in selected manganites. ScholarBank@NUS Repository.
Abstract: In this thesis work, we investigated three intriguing effects, namely colossal electroresistance, magnetoimpedance and magnetocaloric effects in selected Mn- based oxides (manganites). A comprehensive study of both direct and pulsed current/voltage induced electroresistance effects are carried out. We demonstrate various exotic current induced behaviors such as negative differential resistance, magnetoresistance avalanche and first-order metal-insulator transition in certain manganites. We have simultaneously measured the resistivity changes and concomitant thermal response of the samples during the electroresistance effects. Our results underscore the importance of joule heating on CER which is often neglected in earlier works. We also demonstrate a large magnetocaloric effect in certain manganites and suggest that magnetic oxides with nanoscale phase separation, in the paramagnetic phase, can be good candidates for magnetic refrigeration. Finally, we present our exciting results on magnetoimpedance and high frequency electrical transport, mainly, a large low field ac magnetoresistance at room temperature and an unusual field dependence of ac magnetoreactance in a selected manganite.
Appears in Collections:Ph.D Theses (Open)

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