Relationship Between Structure and Magnetic Behaviour in ZnO-Based Systems (eBook)

Clara Guglieri Rodríguez (Autor)

eBook Download: PDF

2015 | 2015
XIV, 146 Seiten
Springer International Publishing (Verlag)
978-3-319-18887-4 (ISBN)

Infos

This work studies the magnetic behavior of ZnO nanoparticles capped with different organic molecules and showing room-temperature ferromagnetism (RTFM). Of particular significance is the combination of element-specific X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) techniques, which demonstrates the intrinsic occurrence of RTFM in these systems and indicates that it is not related to the 3-D states of the metallic cation but is relayed along the conduction band of the semiconductor. The discovery of room-temperature ferromagnetism (RTFM) in semiconductors holds great promise in future spintronics technologies.  
Further results presented here include O K-edge XMCD studies, which demonstrate that the oxygen ions have a ferromagnetic response in these ZnO-based systems, providing the first direct support for claims regarding the appearance of oxygen ferromagnetism in oxide semiconductors at the nanoscale.

Inhalt

Supervisor’s Foreword 9
Contents 11
1 Introduction 13
1.1 State of the Art 13
1.2 Outlook of This Dissertation 17
1.3 Dissertation Structure 18
References 18
2 Synthesis and In-house Characterization of Materials 22
2.1 Synthesis 22
2.1.1 Nanoparticles 22
2.1.2 Thin Films and Multilayers 25
2.2 Structural Characterization 27
2.2.1 X-ray Diffraction (XRD) 27
2.2.2 X-ray Reflectivity (XRR) 31
2.2.3 Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM) and Energy Dispersive X-ray Spectroscopy (EDX) 32
2.3 Optical Absorption 35
2.4 Magnetic Characterization: AC Susceptibility and Magnetization 37
References 45
3 XAS and XMCD Spectroscopies 47
3.1 X-ray Absorption Spectroscopy 48
3.2 X-Magnetic Circular Dichroism 55
3.3 Experimental Methods and Procedures 60
3.3.1 Synchrotron Radiation Facilities 60
3.3.2 BL39XU Beamline at SPring-8 Facility 61
3.3.3 BL25SU Beamline at SPring-8 Facility 66
3.3.4 BL23SU Beamline at SPring-8 Facility 68
3.3.5 XAFS Beamline at Elettra Facility 70
3.4 Ab-Initio Calculations of XANES Spectra 73
References 75
4 Zinc K-edge X-ray Absorption Study of ZnO-Based Magnetic Semiconductors 77
4.1 Zn K-edge XAS Study of ZnO NPs Capped with Organic Molecules ƒ 78
4.2 Zn K-edge XAS Study of ZnO NPs Capped with Thiol Derivatives ƒ 90
4.3 XAS Study of the Local Order Around the Transition Metal on Mn:ZnO ƒ 94
4.4 Conclusions 104
References 105
5 Zinc K-edge XMCD Study of ZnO-Based Magnetic Semiconductors 107
5.1 Zn K-edge and L2,3-edge XMCD Study of ZnO NPs ƒ 107
5.2 Zn K-edge XMCD Study of ZnO NPs Capped with Thiol Derivatives and ZnS/ZnO Thin Films 115
5.3 Conclusions 119
References 120
6 Soft X-ray XAS and XMCD Study of ZnO-Based Magnetic Semiconductors 121
6.1 O K-edge Study of ZnO-Based Materials 122
6.2 S K-edge XAS Study of the Local Structure of Sulphur ƒ 129
6.3 Conclusions 141
References 142
7 Summary and Conclusions 144
Appendices 148

Produkt-Details

• Erscheint lt. Verlag: 3.6.2015
• Reihe/Serie: Springer Theses
• Reihe/Serie: Springer Theses
• Zusatzinfo: XIV, 146 p. 104 illus., 52 illus. in color.
• Verlagsort: Cham
• Sprache: englisch
• Themenwelt: Mathematik / Informatik ► Informatik
• Themenwelt: Naturwissenschaften ► Physik / Astronomie ► Atom- / Kern- / Molekularphysik
• Themenwelt: Technik ► Elektrotechnik / Energietechnik
• Themenwelt: Technik ► Maschinenbau
• Schlagworte: Core-shell structure • magnetic semiconductors • surface magnetism • X-ray absorption spectroscopy • x-ray magnetic circular dichroism • Zinc oxide nanoparticles
• ISBN-10: 3-319-18887-9 / 3319188879
• ISBN-13: 978-3-319-18887-4 / 9783319188874