is crucial for the existence of Meissner effect in this system.

In order to determine the unknown coefficients we need to use the boundary conditions. Henceforth we consider that the anyon fluid is confined to the strip $-\infty <y<\infty $ with boundaries at $x=-L$ and $x=L$. The external magnetic field will be applied from the vacuum at both boundaries ($-\infty
<x\leq -L$, $\;L\leq x<\infty $).

The boundary conditions for the magnetic field are $B\left( x=-L\right)
=B\left( x=L\right) =\overline{B}$ ($\overline{B}$ constant). Because no external electric field is applied, the boundary conditions for this field are, $E\left( x=-L\right) =E\left( x=L\right) =0$. Using them and assuming $%
L\gg \lambda _{1}$, $\lambda _{2}$ ($\lambda _{1}=1/\xi _{1}$, $\lambda
_{2}=1/\xi _{2}$), we find the following relations that give $C_{1,2,3,4}$ in terms of $C_{5}$,

$$C_{1}=Ce^{-L\xi _{1}},\quad C_{2}=-C_{1},\quad C_{3}=-Ce^{-L\xi _{2}},\quad
C_{4}=-C_{3},\quad C=\frac{C_{5}-\overline{B}}{\gamma _{1}-\gamma _{2}} 
\eqnum{3.25}$$

Stability Condition for the Infinite-Strip Sample
=================================================

After using the boundary conditions, we can see from (3.25) that they were not sufficient to find the coefficient $C_{5}$. In order to totally determine the system magnetic response we have to use another physical condition from where $C_{5}$ can be found. Since, obviously, any meaningful solution have to be stable, the natural additional condition to 