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Whether this two-step melting is generic, and how pinning changes it, is open.","posed_since":"","precise":"For a 2D skyrmion lattice in a thin chiral magnet, determine whether melting follows the two-step KTHNY scenario (solid to hexatic to liquid via Kosterlitz-Thouless transitions, with $\\eta_6=1/4$ at the hexatic-liquid transition) or a first-order transition, and how quenched pinning changes the sequence. An answer is the measured or simulated phase diagram with correlation-function exponents.","problem_ref":"0bfcff45aa395e7f30d66862080565ab0d093a9d25d8ad7cefea5b7747bc2468","references":"","settled_by":"Real-space imaging of skyrmion positions in clean films across temperature, analyzed for translational and orientational correlations, with simulations using the measured pinning.","status_note":"Huang et al. (Nature Nanotechnology 2020) observed a hexatic skyrmion phase in thin $\\mathrm{Cu_2OSeO_3}$.","title":"How does a two-dimensional skyrmion lattice 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