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

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Section 2.3<br />

Reflectivity of surface <strong>plasmons</strong> 21<br />

0 1 2 . . . N-1 N N+1<br />

n 0<br />

A 0<br />

B 0<br />

A ’<br />

1<br />

B ’<br />

1<br />

n 1<br />

d 1<br />

A 1<br />

B 1<br />

A ’<br />

2<br />

B ’<br />

2<br />

n 2<br />

d 2<br />

. . .<br />

. . .<br />

. . .<br />

. . .<br />

n N-1<br />

d N-1<br />

A N-1<br />

B N-1<br />

A ’<br />

N<br />

B ’<br />

N<br />

n N<br />

d N<br />

A N<br />

B N<br />

n N+1<br />

A ’<br />

N+1<br />

B ’<br />

N+1<br />

Figure 2.8: Here a sketch of a multilayer system with n layers is shown. 0 and N +1 are not<br />

regarded as layers s<strong>in</strong>ce they are assumed to be semi-<strong>in</strong>f<strong>in</strong>ite half spaces which<br />

cover the multilayer system. Ai represents the amplitude of a right-travell<strong>in</strong>g<br />

wave and Bi the amplitude of a left-travell<strong>in</strong>g wave, both on the left side of<br />

the <strong>in</strong>terface. A ′ i and B′ i<br />

are the amplitudes of right- and left-travell<strong>in</strong>g waves<br />

on the right side of the <strong>in</strong>terface. And ni is the complex refractive <strong>in</strong>dex of the<br />

medium i.<br />

ˆM =<br />

<br />

M11 M12<br />

M21 M22<br />

<br />

= ˆ D01<br />

N<br />

i=1,j=i+1<br />

ˆPi ˆ Dij<br />

x<br />

z<br />

(2.45)<br />

is the so-called transfer matrix ˆ M. The reflection coefficient of a multilayer system<br />

can then be written as the ratio of the reflected wave amplitude (B0) and the <strong>in</strong>cident<br />

amplitude (A0):<br />

r =<br />

B0<br />

With Eq. (2.44) and Eq. (2.45) this yields the reflectivity of a multilayer system.<br />

A0<br />

R = |r| 2 <br />

<br />

= <br />

<br />

<br />

M21<br />

M11<br />

B ′ =0<br />

<br />

<br />

<br />

<br />

2<br />

(2.46)<br />

(2.47)

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