  We present a model to probe metamagnetic properties in systems with an
arbitrary number of interacting spins. Thermodynamic properties such as the
magnetization per particle $m(B,T,N)$, linear susceptibility $\chi_1(T)$,
nonlinear susceptibilities $\chi_3(T)$ and $\chi_5(T)$, specific heat
$C(B,T,N)$, and pressure $P(B,T,N)$ were calculated. The model produces a
different magnetic response for $N$ particles when comparing to $N - 1$
particles for small $N \sim 1$. For an even number of particles, the
susceptibilities show maxima in their temperature dependence. An odd number
produces an additional free spin response that dominates at low temperatures.
This free spin response for odd $N$ also produces a step in the magnetization
per particle at $B = 0$. The magnetization shows $N/2$ steps at $\gamma B_c/J =
n$ with integer $n$ for even $N$ and $(N-1)/2$ additional steps at half-integer
$n$ starting at 3/2 for odd $N$. Small clusters respond with metamagnetism in
an otherwise isotropic spin space, while the large clusters show no
metamagnetism.
