On the Monogenity of Quartic Number Fields Defined by x4 + ax2 + b

For any quartic number field K generated by a root α of an irreducible trinomial of type x4+ax2+b∈Z[x], we characterize when Z[α] is integrally closed. Also for p=2, 3, we explicitly give the highest power of p dividing i(K), the common index divisor of K. For a wide class of monogenic trinomials of this type, we prove that up to equivalence, there is only one generator of power integral bases in K=Q(α). We illustrate our statements with a series of examples.