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

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II Contents 4.2 Reflectivity of multilayer thin films . . . . . . . . . . . . . . . . . . . 56 4.3 Beyond the ideal surface plasmon resonance curve . . . . . . . . . . . 60 4.3.1 Thin film limit . . . . . . . . . . . . . . . . . . . . . . . . . . 60 4.3.2 Surface roughness . . . . . . . . . . . . . . . . . . . . . . . . . 60 4.3.3 Oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 4.3.4 Polarisation effects . . . . . . . . . . . . . . . . . . . . . . . . 64 4.3.5 Immersion oil . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 4.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 5 Surface plasmons in magnetic environments 69 5.1 Surface plasmon resonance at constant magnetic field . . . . . . . . . 69 5.2 Surface plasmon resonance at constant angle . . . . . . . . . . . . . . 73 5.3 Surface plasmons in improved sample structure . . . . . . . . . . . . 76 5.4 Reflectivity at constant magnetic field . . . . . . . . . . . . . . . . . . 79 5.5 Transversal magneto-optical Kerr effect . . . . . . . . . . . . . . . . . 84 5.6 Magnetic anisotropy measurement with TMOKE . . . . . . . . . . . 88 5.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 6 Conclusions and Outlook 93 A Simulation code for the surface plasmon resonance 101 B CAD sketches 105 C Prism correction 107 D Code for SPP simulation after Hermann et al. 111 Bibliography 122
Chapter 1 Introduction Plasmons i.e., longitudinal density fluctuations of quasi-free electrons in a metal, are studied since the early 20th century and can be directly derived from Maxwell’s equa- tions [1, 2]. The first who theoretically investigated plasmons in thin metal films was Ritchie [3], who started the field of surface plasmons with his pioneering work in 1957. In the following years his work was verified by electron-loss spectroscopy experiments and was theoretically extended [4, 5, 6, 7]. In 1968 Kretschmann and Raether introduced their method to excite surface plasmons by light, simply by bringing a metal film in contact with a (glass) prism and coupling the light into the prism [8], allowing to record angle resolved surface plasmon resonances [9]. Prior to the prism coupling method, it was thought no to be possible to excite surface plasmons by light, as the dispersion relation of surface plasmons and the dispersion relation of light do not intersect. But by coupling light into a prism its momentum changes from ω/c to (ω/c) √ ε (0) (ε (0) is the dielectric constant of the prism) and thus both dispersion relations, the one of light and the one of surface plasmons, do cross. In another picture the excitation of surface plasmons is explained by an evanescent wave, which occurs when the light is totally reflected at the prism- metal interface. The evanescent wave has a phase velocity of v = c/( √ ε (0) sin θ0) (θ0 is the incident angle of the light with respect to the normal of the sample surface), which fulfils the resonance condition of surface plasmons for θ0 = θSPP, the surface plasmon resonance angle. Today, the excitation of surface plasmons with light is a well established technique and found its way into many applications, including biosensors [10, 11] or microscopy [12]. Furthermore, with the possibility to pattern and characterise metals on the nanometre scale a new field developed: plasmonics. In this field plasmons are coupled 1
Page 1: TECHNISCHE UNIVERSITÄT MÜNCHEN WA
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 40 and 41: 36 (a) εsubstrate εCo ε prism ε
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
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50 U A-B (θ) [V] 0.00 -0.05 -0.10
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52 U A -B (θ) [V ] U A (θ) [V ] U
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54 will be discussed. 4.1.1.2 Deter
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56 p R 1 .0 0 .8 0 .6 0 .4 0 .2 0 .
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58 p R 0 .8 0 .4 0 .0 0 .8 0 .4
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60 Chapter 4 Experimental study of
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66 4.4 Summary Chapter 4 Experiment
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70 Chapter 5 Surface plasmons in ma
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72 U A -B , -1 5 m T (θ) [V ] 0 .0
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76 Δ θ 0 2 0 1 5 1 0 5 0
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80 ΔU θ = c o n s t (θ) [m V ]
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84 p x 1 0 -4 p /δθ 1 /R δR 0 .5
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86 δU /U (H ) x 1 0 -3 2 .5 2 .0 1
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90 s M /M 1 .5 1 .0 0 .5 0 .0 -0 .5
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94 Chapter 6 Conclusions and Outloo
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100 Chapter 6 Conclusions and Outlo
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102 (*Thickness of the layers in An
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104 /Extract[Ms[lambda, theta], {1,
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106 40 mm 10 mm 130 mm Figure B.2:
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108 and d sin 45 = h/2 sin(90 + θ)
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110 Appendix C Prism correction
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112 Appendix D Code for SPP simulat
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114 (*MO Reflectivity*) Appendix D
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116 Bibliography [12] J. Weeber, E.
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118 Bibliography [40] A. A. Maradud
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120 Bibliography [67] F. E. Luborsk
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122 Bibliography [93] T. Sidiropoul
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Robert Müller, Helmut Thies and hi
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