Abstract

i

Kurzfassung, Acronyms and abbreviations

iii

Contents

vii

Introduction

1

1

Fundamentals

5

1.1

Ferromagnetism in ultrathin 3d bilayer films

5

1.2

Spin-reorientation transition (SRT)

10

1.3

Magnetic domains

21

2

Experimental details

29

2.1

SPLEEM

29

2.2

XMCD

37

2.3

SQUID magnetometry

42

3

Substrate preparation and ultrathin film growth

47

3.1

Preparation of the Cu(100) and GaAs(001) substrates

47

3.2

Growth of ultrathin Ni, Fe and Fe/Ni films on Cu(100) and GaAs(001)

49

4

Design of the UHV-SQUID system

53

4.1

Construction of the UHV chamber

53

4.2

The SQUID sensor

55

4.3

Cryostat and magnetic shielding

55

4.4

The sample holder

56

4.5

Calibration of the SQUID

57

4.6

Data acquisition

59

4.7

Measurements of the stray field of a 12.5 ML Fe/GaAs(001) film

59

5

Magnetic domains

61

5.1

5 to 8 ML Ni on Cu(100)

61

5.2

Evolution of magnetic stripe domains in Fe/Cu(100) films

69

5.3

Fe monolayers on 7 to 11 ML Ni/Cu(100)

72

6

Magnetic domains near the spin-reorientation transition

79

6.1

Continuous reorientation of the magnetization in Ni/Cu(100) films

79

6.2

Spin-reorientation transition of Fe/Ni bilayers on Cu(100)

84

7

Conclusion

107

A

Appendix

111

List of Figures

121

List of Tables

125

References

127

List of publications

139

Acknowledgment

143

Zusammenfassung

145