1.0
julia> (-1^(1/2))
-1.0
julia> Complex((-1)^(1/2))
ERROR: DomainError with -1.0:
Exponentiation yielding a complex result requires a complex argument.
Replace x^y with (x+0im)^y, Complex(x)^y, or similar.
Stacktrace:
[1] throw_exp_domainerror(::Float64) at .\math.jl:35
[2] ^ at .\math.jl:769 [inlined]
[3] ^(::Int64, ::Float64) at .\promotion.jl:345
[4] top-level scope at none:0

One more thing: There is no reason to write Complex(-1+0im). Just write (-1+0im), this is already a complex number, no reason to convert a complex number to (the same) complex number.