ContentsList of FiguresSpintronic MaterialsIntroductionPrior workCobalt-substituted Zinc OxidePreparationExperimental ResultsTheoryMagnetism in Substituted ZnOPreparationResultsModelingSummaryWurtzite Cobalt OxidePrevious workPreparationResultsCalculationsSummaryZnO and Zn1-xCoxO NanoparticlesPreparationResultsSummaryIron-substituted Zinc GallatePreparationResultsSummaryBibliographyUNIVERSITY of CALIFORNIASanta BarbaraMagnetism in Transition-Metal-Substituted Semiconducting OxidesA Dissertation submitted in partial satisfaction of therequirements for the degreeDoctor of PhilosophyinMaterialsbyAditi S. RisbudCommittee in charge:Professor Ram Seshadri, ChairProfessor Anthony K. CheethamProfessor Nicola A. SpaldinProfessor Juergen EckertSeptember 2005The dissertation of Aditi S. Risbud is approved.Professor Anthony K. CheethamProfessor Nicola A. SpaldinProfessor Juergen EckertProfessor Ram Seshadri, Committee ChairAugust 2005Magnetism in Transition-Metal-Substituted Semiconducting OxidesCopyrightc 2005byAditi S. Risbudiiifor my parentsivAcknowledgementsOften as a chapter in one’s life comes to a close, an appreciation for what isabout to be lost begins to surface. It is a credit to Santa Barbara that from themoment of my arrival, I was aware of how fortunate I would be to completemy Ph.D. work in such a beautiful environment. This work would not havebeen possible without the help of my advisor, Ram Seshadri, who I thank forbeing a wonderful advisor these past few years. Ram’s enthusiasm and re-lentless curiosity about science has been an inspiration, and I appreciate all hisguidance over my time here. I must also (grudgingly) admit that I am now aLinux user, and happy about it.My thesis research has been a collaborative effort, and I must thank allthose that have made my dissertation work complete. Nicola Spaldin’s sup-port throughout my thesis has been invaluable; on top of that, she is proba-bly the coolest professor I know. Thanks for the careful reading of my thesis.Gavin Lawes’ straightforward and innovative description of the magnetic be-vhavior of my materials systems lent valuable insight into my research. LaurenSnedeker was a fantastic intern, cheerily plugging away in the lab and helpingmy thesis work along. Mentoring is a highly rewarding part of science andI was happy to work with Lauren, Margaret MacRae and Rey Ho nrada dur-ing my time here. Many thanks to my committee members Tony Cheetham,Juergen Eckert, and David Clarke for their input and suggestions. I must alsothank Z.Q. Chen, S. Stemmer, J.P. Attfield, J. Ensling, C. Felser, M.M. Elcombe,and A.P. Ramirez for their contributions.Before I began my Ph.D. work, there were a number of individuals whohelped in the development of my science abilities. My undergraduate advisorat UC Davis, Alexandra Navrotsky, has an amazing devotion to science, andI thank her for inspiring me to pursue my doctoral degree. I also thank KateHelean for her mentoring and friendship. My next research stint at Caltechwas guided by Harry Atwater. Harry’s ability to communicate science effec-tively resounded with me and sparked the motivation for my current careergoal. I also thank Regina Ragan for being a great mentor and role model dur-ing my time at Caltech. Upon my arrival at UCSB, the Lange group allowedme to make a seamless transition to the Materials department, and I thankFred Lange, Geoff & Denice Fair, Mark & Nicole Snyder, Biao and Zhou, RyanBock, Scott Fillery, Haksung Moon, and Lars Loeffler for their support andvifriendship. Dave Andeen is probably the best officemate I have ever had, andI will miss our conversations about Barry Switzer, the Raiders, Kings, and stay-ing cool, Lakers-style. The Seshadri group has seen a few members come andgo in its relative youth, and I thank our post-docs K. Ramesha and OmbrettaMasala for their help with magnetic measurements and electron microscopy.Eric Toberer and I have spent far too much time together being officemates andthe only graduate students in the Seshadri group, most memorably at MRSBoston, home of the world’s best public transportation Kit Kat. As for MRSSan Francisco- I’m sorry about those contact lenses. I will miss our fashionand color scheme discussions. Someday we’ll compile that list of quotes andpass it on to future group members.The best part of graduate school has been all the great people I have spenttime with, both on and off the court. Jenny Andrew has been a source ofendless friendship, replete with silly accents, Bollywood dance sequences,kothimbeer-laden meals, and lame materials science jokes. Tu kasli whooshaarahes! Thanks for sitting through all my practice talks (and the real ones too).Michael Pontin helped me see the conspiracies of the world, and even thoughhe projects ’bitter old man,’ he is one of the kindest, most thoughtful people Iknow. David Follman has been a great housemate and friend. He is a talentedwriter and a tolerant individual, especially during basketball season. AdamviiPyzyna was a fun housemate and friend, and I will miss watching Chappelleand discussing the latest hip-hop scoop. Emily Parker has been a great friend,workout buddy (only a good friend would be willing to come to Sean’s brutalspin class and save seats) and sounding board for all my ridiculous drama.Remember: You are a Genius. Seth Boeshore has been a fine source of SouthPark quotes and car bomb synergy. Over many a coffee, he has continuallysurprised me with his intellect (beyond just science) and sharp personal ob-servations. Weak. Thanks also to Garrett Cole for discussions on excitons,book hoarding, and general science enthusiasm. Katie Schaefer has been agreat friend, shopping buddy (a convert, in fact) and listener, letting me whineabout my day over a coffee (just not iced) or lunch. Justin Abramson is prob-ably the worst officemate but most interesting friend I’ve had- I will miss ourdiscussions from science to life philosophies. You’ve certainly taught me athing or two about myself, and I appreciate that. Also, thanks for all your helpwith SC. Larken Euliss was our favorite non-Materials person- thanks for in-troducing me to GVAC, bumble & bumble, and ‘thinking in chapters.’ Goodluck at UT Arlington! I must also thank the Materials girls: Felicia Pitek, LisaKinder, Meghan Kerner, Molly Gentleman and Lori Callaghan for a great time,whether it was dancing downtown or in Vegas.There are a few people who let me ignore them for months and then