Microwave Cavity Perturbation on NH₄CuPO₄.H₂O Single Crystals and YBCO Thin Films at Low Temperatures

Bordoloi, Arunav (2016) Microwave Cavity Perturbation on NH₄CuPO₄.H₂O Single Crystals and YBCO Thin Films at Low Temperatures. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Arunav Bordoloi (11MS071)) Arunav_Bordoloi-11MS071.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

In this thesis, cavity perturbation technique has been used to study the dielectric properties of NH₄CuPO₄.H₂O single crystals and YBCO thin films at low temperatures. We employ a cylindrical copper cavity working in TE₀₁₁ mode at 19.5 GHz for our experiment. The dielectric permittivity, magnetic permeability, complex conductivity, penetration depth and surface impedance of NH₄CuPO₄.H₂O crystal has been deduced at various temperatures from the changes of the resonant frequency and Q-factor of the cavity. The crystal was found to be insulating and non-magnetic in nature with high surface resistance. In the case of YBCO thin films, the superconducting transition of YBCO was observed around the temperature of 89 K. However, the full transition could not be observed due to limitations of using a liquid nitrogen cryostat. A sharp increase in the complex conductivity was noticed at this critical temperature using the two- uid model.

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