Fig. (4)
Dependencies of focal distances f
+
and f
–
on value of external homogeneous magnetic field H
0
. α
1
= 5.44×10
-11
cm
2
, α
2
= 6×10
-11
cm
2
, β
1
= 10, β
2
= 15, ρ
2
= 2, L
1
= 25×10
5
cm
-1
, L
2
= 30×10
5
cm
-1
, M
01
= 105 G, m
02
= 95 G, ω = 2×10
11
s
-1
.