MAGNETIC PROPERTIES OF Nb/Ni SUPERCONDUCTING / FERROMAGNETIC MULTILAYERS

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1 University of Kentucky UKnowledge Theses and Dissertations--Physics and Astronomy Physics and Astronomy 2012 MAGNETIC PROPERTIES OF Nb/Ni SUPERCONDUCTING / FERROMAGNETIC MULTILAYERS Sergiy A. Kryukov University of Kentucky, kryukoff@gmail.com Click here to let us know how access to this document benefits you. Recommended Citation Kryukov, Sergiy A., "MAGNETIC PROPERTIES OF Nb/Ni SUPERCONDUCTING / FERROMAGNETIC MULTILAYERS" (2012). Theses and Dissertations--Physics and Astronomy This Doctoral Dissertation is brought to you for free and open access by the Physics and Astronomy at UKnowledge. It has been accepted for inclusion in Theses and Dissertations--Physics and Astronomy by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu.

2 STUDENT AGREEMENT: I represent that my thesis or dissertation and abstract are my original work. Proper attribution has been given to all outside sources. I understand that I am solely responsible for obtaining any needed copyright permissions. I have obtained and attached hereto needed written permission statements(s) from the owner(s) of each third-party copyrighted matter to be included in my work, allowing electronic distribution (if such use is not permitted by the fair use doctrine). I hereby grant to The University of Kentucky and its agents the non-exclusive license to archive and make accessible my work in whole or in part in all forms of media, now or hereafter known. I agree that the document mentioned above may be made available immediately for worldwide access unless a preapproved embargo applies. I retain all other ownership rights to the copyright of my work. I also retain the right to use in future works (such as articles or books) all or part of my work. I understand that I am free to register the copyright to my work. REVIEW, APPROVAL AND ACCEPTANCE The document mentioned above has been reviewed and accepted by the student s advisor, on behalf of the advisory committee, and by the Director of Graduate Studies (DGS), on behalf of the program; we verify that this is the final, approved version of the student s dissertation including all changes required by the advisory committee. The undersigned agree to abide by the statements above. Sergiy A. Kryukov, Student Dr. Lance E DeLong, Major Professor Dr. Tim Gorringe, Director of Graduate Studies

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8 TABLE OF CONTENTS ACKNOWLEDGEMENTS III LIST OF FIGURES... IV LIST OF TABLES...VI CHAPTER ONE - INTRODUCTION Background for Superconductivity Discovery Meissner Effect and London theory Type I/II Superconductors, Quantized Vortices Mixed Phase or Abrikosov Vortex State Microscopic BCS Theory Ferromagnetism Finite Size Effects on Ferromagnetic Ordering The Proximity Effect Superconductor Normal-Metal Structures Superconductor-Ferromagnet Structures Superconductor-Ferromagnet Structures with Uniform Magnetization Density of States Transition Temperature Nonmonotonic Variations The Josephson Effect in S/F/S Junctions...48 CHAPTER TWO - EXPERIMENTAL TECHNIQUES AND RESEARCH TOOLS SQUID Magnetometer AC Measurements DC Measurements SQUID RSO Option Vibrating Reed Technique Transmission Electron Microscopy Polarized Neutron Reflectometry CHAPTER THREE - EXPERIMENTAL RESULTS Nb/Ni Multilayers iv

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