The emergence of superconductivity in 2D materials has attracted much attention and there has been rapid development in recent years because of their fruitful physical properties, such as high transition temperature (Tc), continuous phase transition, and enhanced parallel critical magnetic field (Bc). Tremendous efforts have been devoted to exploring different physical parameters to figure out the mechanisms behind the unexpected superconductivity phenomena, including adjusting the thickness of samples, fabricating various heterostructures, tuning the carrier density by electric field and chemical doping, and so on. Here, different types of 2D superconductivity with their unique characteristics are introduced, including the conventional Bardeen–Cooper–Schrieffer superconductivity in ultrathin films, high‐Tc superconductivity in Fe‐based and Cu‐based 2D superconductors, unconventional superconductivity in newly discovered twist‐angle bilayer graphene, superconductivity with enhanced Bc, and topological superconductivity. A perspective toward this field is then proposed based on academic knowledge from the recently reported literature. The aim is to provide researchers with a clear and comprehensive understanding about the newly developed 2D superconductivity and promote the development of this field much further.

Fermi liquid theory forms the basis for our understanding of the majority of metals, which is manifested in the description of transport properties that the electrical resistivity goes as temperature squared in the limit of zero temperature. However, the observations of strange metal states in various quantum materials , notably high-temperature superconductors 1-10 , bring this spectacularly successful theoretical framework into crisis. Distinct from the quadratic temperature dependence of the electron scattering rate (1/τ) for ordinary metals, strange metals exhibit resistivity that scales linearly with temperature, indicating that the independent quasiparticle approximation in existing theoretical treatment is no longer valid. When 1/τ hits its limit, kBT/ħ where ħ is the reduced Planck's constant, T represents absolute temperature and kB denotes Boltzmann's constant, Planckian dissipation 3,11,12,[22][23][24][25][26] occurs and lends strange metals a surprising link to black holes 27 , gravity [28][29][30][31] , and quantum information theory 24 . While this strange metal phenomenology originates from investigations of only electronic phases, the centrality of a scattering rate dependent only on fundamental constants raises the question of whether it is exclusive to fermionic systems. Here, we show the characteristic signature of strange metallicity arising unprecedentedly in a bosonic system. Our nanopatterned YBa2Cu3O7−δ (YBCO) film arrays reveal T-linear resistance as well as B-linear magnetoresistance over an extended temperature and magnetic field range in a quantum critical region in the phase diagram. Strikingly, the low-field magnetoresistance oscillates with a period dictated by the superconducting flux quantum of h/2e where e is the electron charge and h is the Planck constant, indicating that Cooper pairs instead of single electrons dominate the transport process and the system is bosonic. Moreover, the slope of the T-linear resistance 𝜶 𝐜𝐩 appears bounded by 𝜶 𝐜𝐩 ≈ 𝒉/𝟐𝒆 𝟐 • 𝟏/𝑻 𝐜 𝐨𝐧𝐬𝐞𝐭 where 𝑻 𝐜 𝐨𝐧𝐬𝐞𝐭 is the temperature at which Cooper pairs form, intimating a common scale-invariant transport mechanism corresponding to Planckian dissipation. In contrast to fermionic systems where the temperature and magnetic field dependent scattering rates combine in quadrature 15 of ℏ/𝛕 ≈ ((𝒌 𝑩 𝑻) 𝟐 + (𝝁 𝑩 𝑩) 𝟐 ), both terms linearly combine in the present bosonic system, i.e. ℏ/𝛕 ≈ (𝒌 𝑩 𝑻 + 𝜸𝝁 𝑩 𝑩) , where 𝜸 is a constant. By extending the reach of strange metal phenomenology to a bosonic system, our results suggest that there is a fundamental principle governing their transport which transcends particle statistics.