Discovery of Co-existing Non-collinear Spin Textures in D2d Heusler Compounds

Supervisor’s Foreword
Abstract
	Publications related to this thesis
Acknowledgements
Contents
Abbreviations
1 Introduction
	References
2 Magnetic Skyrmions
	2.1 Non-collinear Magnetism
	2.2 Magnetic Skyrmions
	2.3 Magnetic Antiskyrmions
	2.4 Topological Definition of Skyrmions
	2.5 Energy Terms for Stabilizing Skyrmions
		2.5.1 Exchange Interaction
		2.5.2 Zeeman Interaction and Anisotropies
		2.5.3 Dzyaloshinskii-Moriya Interaction
		2.5.4 Dipole–Dipole Interactions
	2.6 Towards Application of Skyrmions
	2.7 Stabilization of Different Spin Textures in Single Material System
	2.8 Summary
	References
3 Experimental Methods
	3.1 Magnetization Measurement
	3.2 Scanning Electron Microscopy and Electron Backscatter Diffraction
	3.3 Focused Ion Beam
	3.4 Transmission Electron Microscopy
	3.5 Electron Diffraction
	3.6 Lorentz Transmission Electron Microscopy
	3.7 High-Resolution and Scanning Transmission Electron Microscopy
	3.8 Summary
	References
4 Elliptical Bloch Skyrmions and Antiskyrmions in a D2d Inverse Heusler Compound
	4.1 Introduction
	4.2 Methods
		4.2.1 Experimental Details
		4.2.2 Micromagnetic Simulations
	4.3 Results and Discussion
		4.3.1 Round and Square Antiskyrmions
		4.3.2 Elliptical Bloch Skyrmions
		4.3.3 Enhanced Stability of Elliptical Bloch Skyrmions
		4.3.4 Elliptical Bloch Skyrmion Chiral Twins
		4.3.5 Switching Between Round and Square Antiskyrmions
		4.3.6 Simultaneous Existence of Elliptical Skyrmions and Antiskyrmions
		4.3.7 Magnetic Phase Diagram
	4.4 Summary
	References
5 Evolution and Competition Between Chiral Spin Textures in Nano-stripes
	5.1 Introduction
	5.2 Methods
		5.2.1 Experimental Details
		5.2.2 Micromagnetic Simulations
	5.3 Result and Discussion
		5.3.1 Nano-stripes Along Different Crystallographic Directions
		5.3.2 Helices and Antiskyrmions in [010] Oriented Nano-stripes
		5.3.3 Difference Between Helices and Other Domains in D2d System
		5.3.4 Antiskyrmion Chains in Differently Oriented Nano-stripes
		5.3.5 Co-existence of Elliptical Skyrmions and Antiskyrmions at Room Temperature
	5.4 Summary
	References
6 Stability, Collapse Dynamics and Fractional Form of Antiskyrmions and Elliptical Bloch Skyrmions
	6.1 Introduction
	6.2 Experimental Details
	6.3 Results and Discussion
		6.3.1 Metastability of Square Antiskyrmions
		6.3.2 Collapse Dynamics of Antiskyrmions and Elliptical Skyrmions
		6.3.3 Fractional Elliptical Bloch Skyrmions and Antiskyrmions
		6.3.4 In-Plane Field Dependent Metastability of Spin Textures
		6.3.5 Evaluation of Spin Textures from the Helical State
		6.3.6 Stability of Elliptical Bloch Skyrmions Against Heating
	6.4 Summary
	References
7 Observation of Antiskyrmions and Bloch Skyrmions in a Low Moment Ferrimagnetic Heusler Compound
	7.1 Introduction
	7.2 Experimental Methods
		7.2.1 Bulk Polycrystalline Synthesis
		7.2.2 Powder XRD, EDXS, and EBSD
		7.2.3 Magnetization Measurements
		7.2.4 Microscopy Characterizations
	7.3 Results and Discussion
		7.3.1 Magnetic Antiskyrmions in Mn2Rh0.95Ir0.05Sn
		7.3.2 Field Driven Formation of Antiskyrmions
		7.3.3 Helical Periods of Mn2Rh0.95Ir0.05Sn and Mn1.4Pt0.9Pd0.1Sn
		7.3.4 Bloch Skyrmions in Mn2Rh0.95Ir0.05Sn
		7.3.5 Field Driven Formation of Bloch Skyrmions
		7.3.6 Stability of Bloch Skyrmions Against Heating
	7.4 Summary
	References
8 Conclusion and Outlook
	8.1 Conclusion
	8.2 Future Perspectives
	References
Appendix A Supplementary Figure for Elliptical Bloch Skyrmions and Antiskyrmions in a D2d Inverse Heusler Compound
A.1 Elliptical Bloch Skyrmions at 150 and 250 K
Appendix B Supplementary Figures for Evolution and Competition Between Chiral Spin Textures in Nano-stripes
B.1 Effect of Field on Helix and Magnetic Domain
B.2 Single, Double and Elongated Antiskyrmions at 490 nm Width Stripe
Appendix C Supplementary Figures for Stability, Collapse Dynamics and Fractional Form of Antiskyrmions and Elliptical Bloch Skyrmions
C.1 Transition Between the Antiskyrmion and Helices
C.2 Effect of In-Plane Field Component on Antiskyrmion
C.3 Elliptical Bloch Skyrmion in the Field Increasing Mode
Curriculum Vitae