Question: How I can plot a function with complex terms

Could please help me what is the problem of the following and how I can plot it

restart;
with(LinearAlgebra);
with(plots, implicitplot);
M := Matrix([[sigma + Gamma*ik + 0.5 + 0.5*tanh(c - v) + beta*v, -0.5 + 0.5*tanh(c - v), 0.5*(w - u)*sech^2*(c - v) - beta*u], [-0.5 - 0.5*tanh(c - v), sigma - i*k*Gamma + 0.5 + 0.5*tanh(c - v) + beta*v, 0.5*(u - w)*sech^2*(c - v) - beta*w], [-beta*v, -beta*v, sigma - beta*alpha*(u + w)]]):

Eq := Determinant(M):

alpha := 0.1;
beta := 0.01;
mu := 0.5;
u := 0.5;
v := 1;
Gamma := 0.1;
c := 2;
w := 0.5;

p1r := evalc(Re(Eq)):

p1 := implicitplot(Eq, k = 0 .. 10, sigma = -0.01 .. 0.01);
Error, (in plots/implicitplot) invalid input: the following extra unknowns were found in the input expression: {i, ik}