  Intrinsic spin angular-momentum coupling of an electron has a relativistic
quantum origin with the coupling arising from charged-orbits, which does not
carry over to charge-neutral atoms. Here we propose a mechanism of spontaneous
generation of spin angular-momentum coupling with spinor atomic bosons loaded
into $p$-orbital bands of a two-dimensional optical-lattice. This spin
angular-momentum coupling originates from many-body correlations and
spontaneous symmetry breaking in a superfluid, with the key ingredients
attributed to spin-channel quantum fluctuations and an approximate rotation
symmetry. The resultant spin angular-momentum intertwined superfluid has Dirac
excitations. In presence of a chemical potential difference for adjacent sites,
it provides a bosonic analogue of a symmetry-protected-topological insulator.
Through a dynamical mean-field calculation, this novel superfluid is found to
be a generic low-temperature phase, and it gives way to Mott localization only
at strong interactions and even-integer fillings. We show the temperature to
reach this order is accessible with present experiments.
