Comment on ``New Vortex-Matter Size Effect Observed in Bi₂Sr₂CaCu₂O₈₊δ"

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The Letter of Wang et al. wan is related to the recently discovered vanishing of the second magnetization peak (SMP) in high-Tc superconductors reducing the sample size kope1,kope2,gal. This phenomenon has been interpreted kope1,kope2,gal in terms of thermomagnetic instability (TMI) effects. The TMI approach has also been adopted by Wang et al. in their previous work wan2 on the critical sample size temperature dependence Rcr(T) measured in Bi₂Sr₂CaCu₂O₈₊δ (Bi2212) single crystals. In contrast, in the recently published Letter wan the authors claimed that the Rcr(T) obtained for Bi2212 crystals is at odds with the TMI model and proposed an alternative explanation of the results assuming that the SMP vanishes as the sample width (or diameter) becomes smaller than the in-plane vortex correlation length Rc²ᵈ(T) Jc(T)⁻¹/², where Jc(T) is the critical current density. We demonstrate below that the authors conclusion is misleading.