Surface magneto-plasmons in magnetic multilayers - Walther ...

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36 (a) εsubstrate εCo ε prism ε Au εAu εair 5 mm Chapter 3 Excitation of surface plasmon polaritons (b) 5 mm Figure 3.3: (a) Sketch of the 5mm prism with a trilayer sample (the dimensions are not to scale). (b) Photograph of the 5 mm prism and a trilayer sample which is brought into contact with the prism by an immersion oil. (AS411-E) with position controllers (SMCI33) from Nanotec were used. The stepper motors are 1.8 ◦ stepper motors operated in the full step mode and since 200 steps are needed for turning the table 1 ◦ , a mechanical angle resolution of 0.005 ◦ should be possible. When assuming an error of ±1 steps a resolution of 0.01 ◦ should still be feasible. In this thesis the smallest angle step size used is 0.1 ◦ . To place the prism in the optical path a prism stage was designed, which consists of two parts. One part is designed to fit directly onto the inner rotation stage. And the other part is designed to adjust the prism’s position. The second part has to meet two requirements: one is to simplify the adjustment of the prism in the optical path and the other is that the prism is positioned on the rotation axis. To simplify the positioning of the prism in the optical path, there is a mark running in radial direc- tion from the rotation axis, allowing for the alignment of the prism (see Fig. 3.4 and Appendix B). To fulfil the second requirement, perpendicular to the mark there is a step over the centre of rotation at which the prism can be aligned 3 . The two parts of the prism stage are connected by distance pieces, which are mounted in between of both stages. Further, the rotation stage has three support structures which can be rotated indi- vidually. With these the height and the decline of the table can be adjusted. 3 Actually it is 1 mm off-axis, because in the beginning it was assumed that the sample, which is mounted on the back of the prism, has a thickness of 1 mm
Section 3.1 Experimental setup 37 prism centre of rotation incident laser beam step mark Figure 3.4: The figure shows a sketch of the prism stage and how the prism can be adjusted with the help of the mark and the step. Further, the black vertical line represents the centre of rotation and the red line the incident laser beam. Magnetic field The magnetic field is produced by a home-built electromagnet. The requirements for the magnet are a homogeneous magnetic field of µ0H > 20 mT, as the coercive field of thin Co film is µ0HC ≈ 1 − 20 mT 4 [65, 66, 67]. To calculate the maximum magnetic field in the air gap of the electromagnet, the concept of a magnetic circuit is used [68]. To this end we start from Ampère’s law s Hds = nI. (3.1) Here H is the magnetic field, n the number of turns, I the current through the coil, and s the integration path (cf. Fig. 3.5(a)). This yields with H = B/(µ0µr) B = lF e µ0µr nI + gair µ0 , (3.2) where µ0 = 4π × 10 −7 As/Vm is the vacuum permeability and µr ≈ 50 5 [71] the permeability in a medium, in our case steel. 4 µ0HC, strongly depends on the film thickness 5 µr can vary for different iron alloys over some orders of magnitude [69, 70]. Here µr of a steel with 0.9 % C is chosen, since this is a common used steel type.
Page 1: TECHNISCHE UNIVERSITÄT MÜNCHEN WA
Page 4 and 5: II Contents 4.2 Reflectivity of mul
Page 6 and 7: 2 Chapter 1 Introduction via a grat
Page 8 and 9: 4 Chapter 1 Introduction
Page 10 and 11: 6 angular frequency, t the time, an
Page 12 and 13: 8 Chapter 2 Theory Here, µ (1) =
Page 14 and 15: 10 electron density. Chapter 2 Theo
Page 16 and 17: 12 Chapter 2 Theory [8]. In this co
Page 18 and 19: 14 2.3.1 Reflectivity of a single l
Page 20 and 21: 16 Chapter 2 Theory curve shown in
Page 22 and 23: 18 t 10 t 10 t 10 r 01 E 0 r 10 e i
Page 24 and 25: 20 Chapter 2 Theory Hereby, i = 1,
Page 26 and 27: 22 2.4 Simulation of the reflectivi
Page 28 and 29: 24 dopt = |ε ′(1) | − 1 4π |
Page 30 and 31: 26 p R 1 .0 0 .8 0 .6 0 .4 0 .2 0 .
Page 32 and 33: 28 2.5.1 Interaction of an external
Page 34 and 35: 30 ω |k x | Chapter 2 Theory Figur
Page 36 and 37: 32 Chapter 2 Theory enhancement wil
Page 38 and 39: 34 LASER lter beam splitter polaris
Page 42 and 43: 38 Chapter 3 Excitation of surface
Page 46 and 47: 42 p h o to -d e te c to r s ig n a
Page 48 and 49: 44 9 0 8 5 8 0 7 5 7 0 6 5 6
Page 50 and 51: 46 5 V 0 V U out Chapter 3 Excitati
Page 54 and 55: 50 U A-B (θ) [V] 0.00 -0.05 -0.10
Page 56 and 57: 52 U A -B (θ) [V ] U A (θ) [V ] U
Page 58 and 59: 54 will be discussed. 4.1.1.2 Deter
Page 60 and 61: 56 p R 1 .0 0 .8 0 .6 0 .4 0 .2 0 .
Page 62 and 63: 58 p R 0 .8 0 .4 0 .0 0 .8 0 .4
Page 64 and 65: 60 Chapter 4 Experimental study of
Page 70 and 71: 66 4.4 Summary Chapter 4 Experiment
Page 74 and 75: 70 Chapter 5 Surface plasmons in ma
Page 76 and 77: 72 U A -B , -1 5 m T (θ) [V ] 0 .0
Page 80 and 81: 76 Δ θ 0 2 0 1 5 1 0 5 0
Page 84 and 85: 80 ΔU θ = c o n s t (θ) [m V ]
Page 88 and 89: 84 p x 1 0 -4 p /δθ 1 /R δR 0 .5
Page 90 and 91:
86 δU /U (H ) x 1 0 -3 2 .5 2 .0 1
Page 92 and 93:
88 Chapter 5 Surface plasmons in ma
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90 s M /M 1 .5 1 .0 0 .5 0 .0 -0 .5
Page 96 and 97:
92 Chapter 5 Surface plasmons in ma
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94 Chapter 6 Conclusions and Outloo
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
100 Chapter 6 Conclusions and Outlo
Page 106 and 107:
102 (*Thickness of the layers in An
Page 108 and 109:
104 /Extract[Ms[lambda, theta], {1,
Page 110 and 111:
106 40 mm 10 mm 130 mm Figure B.2:
Page 112 and 113:
108 and d sin 45 = h/2 sin(90 + θ)
Page 114 and 115:
110 Appendix C Prism correction
Page 116 and 117:
112 Appendix D Code for SPP simulat
Page 118 and 119:
114 (*MO Reflectivity*) Appendix D
Page 120 and 121:
116 Bibliography [12] J. Weeber, E.
Page 122 and 123:
118 Bibliography [40] A. A. Maradud
Page 124 and 125:
120 Bibliography [67] F. E. Luborsk
Page 126 and 127:
122 Bibliography [93] T. Sidiropoul
Page 128:
Robert Müller, Helmut Thies and hi
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