Structures in plasma equilibria have been studied with discussing the symmetry and its breaking. Structures in physics have been separated into two different classes one is a class of extrinsic structures which are characterized in responses to external conditions, and the other is a class of intrinsic structures which are intrinsically internal structures. An eigenfunction of a Schrödinger operator is a typical example of an intrinsic structure. A plasma equilibrium is also an example of an intrinsic structure. The free-decay plasma equilibrium is a distinguished dissipative structure which is self-organized through fluctuations of global kink modes. The intrinsic structure of the free-decay equilibrium has been studied by analyzing the spectra of the differential operator rot. The voltex fields are quantumized by the spectral resolution of the self-adjoint rotation operator. A free-decay state usually has a symmetry induced by the cohomology of the torus. The symmetry breaking (bifurcation) occurs at a discrete eigenvalue of the self-adjoint rot through a superposition of a corresponding quantumized voltex.