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FIG. 3: Scaled structure-factor peak S ( Q ) /N p as a function of applied force. Here ⃗ Q stands for the primary reciprocal lattice vector for either the c (2 × 2) phase ( ⃗ k c ) or the hexagonal phase ( ⃗ k $_{h}$). Filled and open symbols correspond to increasing and decreasing forces, respectively. 

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6-fold coordinated peaks at the reciprocal lattice vectors ⃗ Q = ⃗ k$_{h}$ corresponding to a hexagonal phase, which grows as the driving force increases. This implies that at a driving force larger than this third threshold f$_{c}$ , there is another dynamic continuous transition from a disor- dered phase into an incommensurate hexagonal phase. This state emerges as the average effect of the external pinning potential becomes less and less important at high sliding velocities and the steady state then approximately corresponds to the phase-field crystal in the absence of the pinning potential which has hexagonal symmetry in the equilibrium state. However, since the scaled struc- ture factor for the hexagonal phase is still much less than unity, this incommensurate hexagonal phase is not fully ordered even at at the largest force values ( f < 0 . 15) studied so far. 

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