  We theoretically demonstrate that a pair of Dirac monopoles with opposite
synthetic charges can be created within a single spin-1 Bose-Einstein
condensate by steering the spin degrees of freedom by external magnetic fields.
Although the net synthetic magnetic charge of this configuration vanishes, both
the monopole and the antimonopole are accompanied by vortex filaments carrying
opposite angular momenta. Such a Dirac dipole can be realized experimentally by
imprinting a spin texture with a nonlinear magnetic field generated by a pair
of coils in a modified Helmholtz configuration. We also investigate the case
where the initial state for the dipole-creation procedure is pierced by a
quantized vortex line with a winding number k. It is shown that if k = -1, the
resulting monopole and antimonopole lie along the core of a singly quantized
vortex whose sign is reversed at the locations of the monopoles. For k = -2,
the monopole and antimonopole are connected by a vortex line segment carrying
two quanta of angular momentum, and hence the dipole as a whole is an isolated
configuration. In addition, we simulate the long-time evolution of the dipoles
in the magnetic field used to create them. For k = 0, each of the semi-infinite
doubly quantized vortices splits into two singly quantized vortices, as in the
case of a single Dirac monopole. For k = -1 and k = -2, the initial vortices
deform into a vortex with a kink and a vortex ring, respectively.
