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arXiv2026

Selective effects of selenium substitution on superconductivity and magnetic memory in 4Hb-TaS2

Disorder plays a central role in correlated quantum materials, but its effects can be highly selective when several electronic orders coexist. The van der Waals heterostructure 4Hb-TaS2 provides such a case, combining superconductivity, charge-order tendencies, strong scattering, and magnetic memory manifested through spontaneous vortices. Here we use Se substitution as a controlled local perturbation of the disorder landscape in 4Hb-TaS2. We find that superconductivity remains remarkably robust while the magnetic memory is strongly suppressed at higher Se concentrations. These results show that Se substitution does not create the hidden magnetic memory, but instead selectively weakens its macroscopic manifestation. More broadly, they reveal a sharp separation between robust superconducting and hidden-memory phases, and a highly disorder-sensitive spontaneous-vortex response in 4Hb-TaS2.

cond-mat.supr-con↗

arXiv2026

Evidence for an effective gauge field in flakes of superconducting 4Hb-TaS2

Understanding the normal state of unconventional superconductors is central to uncovering the origin of superconductivity itself. Unconventional superconductivity often emerges from correlated electronic states characterized by intertwined symmetry-breaking orders. A striking example is 4Hb-TaS2, whose superconducting state exhibits a remarkable range of phenomena, including an unusual magnetic memory effect. Previous experiments showed that magnetic memory can be encoded above Tc and later revealed through spontaneous vortices below Tc, suggesting time-reversal symmetry breaking. However, since memory and vorticity are intertwined, this prevents establishing whether the effect results from trapped flux, weak conventional magnetism, or a true hidden electronic order. Here, we show that magnetic memory persists in the vortex-free Meissner regime of exfoliated 4Hb-TaS2 flakes, where it appears as a stable remanent modification of the superconducting screening response. Our results rule out explanations based on trapped vortices. Furthermore, the spatial profile of the flux generated by trained samples at zero field is inconsistent with conventional weak magnetism, suggesting a hidden electronic phase that imprints an effective flux on the superconducting condensate.

cond-mat.supr-con↗