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Effect of microstructure on the magnetic properties of transition metal implanted TiO2 films

Bibliographic Details
Authors and Corporations: Yildirim, Oguz
Title Statement: Effect of microstructure on the magnetic properties of transition metal implanted TiO2 films
Dissertation Note: Dissertation, Technische Universität Dresden, 2016
Type of Resource: E-Book
Subjects:
?> Table of Contents:
  • 1 Introduction 2 1.1 Spintronics 2 1.2 Dilute magnetic oxides 5 2 Fundamentals 13 2.1 Introduction 13 2.2 Magnetism in diluted magnetic oxides 13 2.2.1 Possible locations of dopant 3d ions in an oxide matrix 14 2.2.2 Mean field model 15 2.2.3 Bound magnetic polaron model 16 2.2.4 Charge transfer model 17 2.2.5 Ferromagnetism in undoped oxides 19 2.2.6 Extrinsic sources of ferromagnetism 20 2.3 Motivation 21 3 Experimental 24 3.1 Sample preparation 24 3.1.1 DC magnetron sputtering 24 3.1.2 Ion implantation 27 3.2 X-ray methods 29 3.2.1 X-ray diffraction 29 3.2.2 X-ray absorption 31 3.2.2.1 Synchrotron radiation 31 3.2.2.2 Physics of X-ray absorption 31 3.3 SQUID magnetometry 35 3.3.1 Avoiding magnetic contamination 37 3.4 Positron annihilation spectroscopy 38 4 TM Implantation into Different TiO2 Structures (TM = Co, Mn, V) 43 4.1 Experiments 43 4.2 Co+ implantation: from diluted paramagnetism to superparamagnetic clusters 45 4.2.1 Cluster-free Co+-implanted TiO2 thin films 45 4.2.1.1 Experiments 45 4.2.1.2 Structural properties 46 4.2.1.3 Implantation-induced structural defects 47 4.2.1.4 Magnetic properties 50 4.2.1.5 Local environment of implanted Co atoms 51 4.2.1.6 Summary 52 4.2.2 Revealing nano-clusters within Co+-implanted TiO2 thin films 54 4.2.2.1 Experiments 54 4.2.2.2 Structural properties 54 4.2.2.3 Magnetic properties 57 4.2.2.4 Local environment of implanted Co atoms 59 4.2.2.5 Summary 61 4.3 Mn+ implantation: from a non-magnet to a ferromagnet 63 4.3.1 Experiments 63 4.3.2 Relation between lattice damage and defects 64 4.3.3 Electrical transport properties 65 4.3.4 Local environment of implanted Mn atoms 66 4.3.5 Magnetic properties 67 4.3.6 Summary 69 4.4 V+-implanted TiO2 thin films 71 4.4.1 Experiments 71 4.4.2 Magnetic properties 71 4.4.3 Summary 74 5 The effect of the open volume defects on the magnetic properties of V:TiO2 films prepared by doping during deposition 76 5.1 Experiments 76 5.2 Structural Properties 77 5.3 Investigation of the open volume defects 78 5.4 Magnetic, optical and electrical properties 79 5.5 Summary 81 6 Conclusions 84 6.1 Defects in TiO2 84 6.2 Formation of secondary phases 85 6.3 Evolution of the ferromagnetism in different microstructures of TiO2 87 7 Acknowledgments 91