| Summary: | We derive a three-dimensional Dirac-cone structure composed of tilted anisotropic Dirac cones around spirally located Dirac points. The Dirac points form a nodal spiral in momentum space due to accidental degeneracy, which can be realized in rhombohedral graphite. Under the interlayer electron hoppings, the Dirac cone varies in orientation and shape along this Dirac-point spiral, like a magic gyro precessing and deforming with time. The cone precession is governed by the hopping along the rhombohedral primitive unit vectors. In a perpendicular magnetic field, the electron orbits are related to different Landau level energies under the same quantization condition. The Landau subbands are thus characterized by a dispersion factor in addition to the zero-mode spectrum determined by the Dirac-point spiral.
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