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In Quiescent H-mode (QH-mode), edge-localized modes (ELMs) are naturally replaced by a low- n edge harmonic oscillation (EHO), yet the self-regulating transport mechanism driven by the EHO remains insufficiently understood. Using high-spatiotemporal-resolution imaging diagnostics on KSTAR—electron cyclotron emission imaging and broadband electron cyclotron emission—we resolve the eigenmode structure of the EHO and elucidate its regulatory role in edge transport. The EHO is localized within the pedestal near the maximum pressure gradient, propagates in the ion-diamagnetic direction, and its radial envelope expands with increasing shear, suggesting that rotational shear is closely associated with the structural evolution of the EHO. Information-theoretic Transfer Entropy analysis identifies a distinct ‘dual-stabilization’ regulatory interaction pattern: the EHO is associated with enhanced outward energy transport to limit the pressure gradient, while the background shear flow is associated with preferential regulatory influence on the EHO saturation amplitude and energy flux. These results demonstrate that the QH-mode pedestal is sustained by a shear-associated regulation mechanism, where the coupling between rotational shear and mode structure appears closely linked to the sustained ELM-free state.

The pursuit of discovering new high-temperature superconductors that diverge from the copper-based model 1 – 3 has profound implications for explaining mechanisms behind superconductivity and may also enable new applications 4 – 8 . Here our investigation shows that the application of pressure effectively suppresses the spin–charge order in trilayer nickelate La 4 Ni 3 O 10− δ single crystals, leading to the emergence of superconductivity with a maximum critical temperature ( T c ) of around 30 K at 69.0 GPa. The d.c. susceptibility measurements confirm a substantial diamagnetic response below T c , indicating the presence of bulk superconductivity with a volume fraction exceeding 80%. In the normal state, we observe a strange metal behaviour, characterized by a linear temperature-dependent resistance extending up to 300 K. Furthermore, the layer-dependent superconductivity observed hints at a unique interlayer coupling mechanism specific to nickelates, setting them apart from cuprates in this regard. Our findings provide crucial insights into the fundamental mechanisms underpinning superconductivity, while also introducing a new material platform to explore the intricate interplay between the spin–charge order, flat band structures, interlayer coupling, strange metal behaviour and high-temperature superconductivity. The application of pressure effectively suppresses the spin–charge order in trilayer nickelate La 4 Ni 3 O 10− δ single crystals, leading to the emergence of superconductivity.

The Ruddlesden–Popper (R–P) bilayer nickelate, La 3 Ni 2 O 7 , was recently found to show signatures of high-temperature superconductivity (HTSC) at pressures above 14 GPa (ref.  1 ). Subsequent investigations achieved zero resistance in single-crystalline and polycrystalline samples under hydrostatic pressure conditions 2 – 4 . Yet, obvious diamagnetic signals, the other hallmark of superconductors, are still lacking owing to the filamentary nature with low superconducting volume fraction 2 , 4 , 5 . The presence of a new 1313 polymorph and competing R–P phases obscured proper identification of the phase for HTSC 6 – 9 . Thus, achieving bulk HTSC and identifying the phase at play are the most prominent tasks. Here we address these issues in the praseodymium (Pr)-doped La 2 PrNi 2 O 7 polycrystalline samples. We find that substitutions of Pr for La effectively inhibit the intergrowth of different R–P phases, resulting in a nearly pure bilayer structure. For La 2 PrNi 2 O 7 , pressure-induced orthorhombic to tetragonal structural transition takes place at P c  ≈ 11 GPa, above which HTSC emerges gradually on further compression. The superconducting transition temperatures at 18–20 GPa reach T c onset = 82.5 K and T c zero = 60 K , which are the highest values, to our knowledge, among known nickelate superconductors. Importantly, bulk HTSC was testified by detecting clear diamagnetic signals below about 75 K with appreciable superconducting shielding volume fractions at a pressure of above 15 GPa. Our results not only resolve the existing controversies but also provide directions for exploring bulk HTSC in the bilayer nickelates. Bulk high-temperature superconductivity observed in pressurized tetragonal La 2 PrNi 2 O 7 was testified by detecting clear diamagnetic signals below about 75 K with appreciable superconducting shielding volume fractions at a pressure of above 15 GPa.

There is a long-standing apparent conflict between the existence of diamagnetism and causality as expressed through the Kramers-Kronig relations. In essence, using causality arguments, along with a small number of seemingly well-justified assumptions, one can show that diamagnetism is impossible. However, experiments show diamagnetic responses from magnetic media. We present a resolution to this issue, which also explains the absence of observed dia-electric responses in media. In the process, we expose some of the short-comings in earlier analyses that have kept the paradox alive.

The discovery of Ruddlesden–Popper (RP) bilayer nickelate superconductors under high pressure has opened a new chapter in high-transition-temperature superconductivity 1 , 2 , 3 , 4 , 5 , 6 , 7 – 8 . However, the high-pressure conditions and presence of impurity phases have hindered comprehensive investigations into their superconducting properties and potential applications. Here we report ambient-pressure superconductivity onset above the McMillan limit (40 K) in RP bilayer nickelate epitaxial thin films. Three-unit-cell-thick La 2.85 Pr 0.15 Ni 2 O 7 pure-phase single-crystal films are grown using the gigantic-oxidative atomic layer-by-layer epitaxy on SrLaAlO 4 substrates 9 . Resistivity measurements and magnetic field responses indicate onset transition temperature of 45 K. The transition to zero resistance shows characteristics consistent with a Berezinskii–Kosterlitz–Thouless (BKT) behaviour, with T BKT  = 9 K. The Meissner diamagnetic effect is observed at 8 K by using a mutual inductance setup, in agreement with the BKT-like transition. In- and out-of-plane critical magnetic fields show anisotropy. Scanning transmission electron microscopy images and X-ray reciprocal space mappings reveal that the RP bilayer nickelate films adopt a tetragonal phase under roughly 2% coherent epitaxial compressive strain in the NiO 2 planes relative to the bulk. Our findings pave the way for comprehensive investigations of nickelate superconductors under ambient pressure conditions and for exploring superconductivity at higher transition temperatures through strain engineering in heterostructures. Ambient-pressure superconductivity onset above the McMillan limit in bilayer nickelate epitaxial thin films is reported, paving the way for comprehensive investigations of superconductors and for exploring superconductivity at higher transition temperatures in heterostructures.

Diamagnetism, in which the magnetisation in a medium opposes the direction of an applied magnetic field, is a weak but familiar effect in a wide class of materials. Being weak it is also a linear response to any applied field. The problem is that the existence of diamagnetism is in direct conflict with the requirements of causality as embodied in the familiar Kramers-Kronig relations. Nature does not care about our confusion and diamagnetism exists and physics is constrained by the requirements of causality (that effect cannot precede its cause). This puzzle has received intermittent attention from time to time, with a variety of arguments made to resolve the paradox. None of these, no matter how plausible, reveal the mechanism that resolves the existence of diamagnetism without sacrificing causality. The full resolution is presented in this letter.

In this paper, we analyze the magnetic Dirichlet-to-Neumann operator (D-to-N map) \\( (b,)\\) on the exterior of the disk with respect to a magnetic potential \\(A_b, =A^b + A_\\) where, for \\(bın R\\) and \\( ın R\\), \\(A^b (x,y)= b\\, (-y, x)\\) and \\(A_ (x,y)\\) is the Aharonov-Bohm potential centered at the origin of flux \\(2 \\). First, we show that the limit of \\( (b,)\\) as \\(b 0\\) is equal to the D-to-N map \\( ()\\) on the interior of the disk associated with the potential \\(A_ (x,y)\\). Secondly, we study the ground state energy of the D-to-N map \\( (b,)\\) and show that the strong diamagnetism property holds. Finally we slightly extend to the exterior case the asymptotic results obtained in the interior case for general domains.

In semiconductor physics, many essential optoelectronic material parameters can be experimentally revealed via optical spectroscopy in sufficiently large magnetic fields. For monolayer transition-metal dichalcogenide semiconductors, this field scale is substantial—tens of teslas or more—due to heavy carrier masses and huge exciton binding energies. Here we report absorption spectroscopy of monolayer MoS 2 , MoSe 2 , MoTe 2 , and WS 2 in very high magnetic fields to 91 T. We follow the diamagnetic shifts and valley Zeeman splittings of not only the exciton’s 1 s ground state but also its excited 2 s , 3 s , … , n s Rydberg states. This provides a direct experimental measure of the effective (reduced) exciton masses and dielectric properties. Exciton binding energies, exciton radii, and free-particle bandgaps are also determined. The measured exciton masses are heavier than theoretically predicted, especially for Mo-based monolayers. These results provide essential and quantitative parameters for the rational design of opto-electronic van der Waals heterostructures incorporating 2D semiconductors. The rational design of optoelectronic devices based on 2D materials relies on quantitative knowledge of their excitonic properties. Here the authors perform circularly-polarized absorption spectroscopy on monolayer MoS 2 , MoSe 2 , MoTe 2 and WS 2 in magnetic fields up to 91 T, and derive the effective exciton masses, binding energies, radii, dielectric properties, and free-particle bandgaps of these monolayer semiconductors

Magnetic two-dimensional materials have attracted considerable attention for their significant potential application in spintronics. In this study, we present a high-quality Fe-doped SnS 2 monolayer exfoliated using a micromechanical cleavage method. Fe atoms were doped at the Sn atom sites, and the Fe contents are ∼2.1%, 1.5%, and 1.1%. The field-effect transistors based on the Fe 0.021 Sn 0.979 S 2 monolayer show n-type behavior and exhibit high optoelectronic performance. Magnetic measurements show that pure SnS 2 is diamagnetic, whereas Fe 0.021 Sn 0.979 S 2 exhibits ferromagnetic behavior with a perpendicular anisotropy at 2 K and a Curie temperature of ~31 K. Density functional theory calculations show that long-range ferromagnetic ordering in the Fe-doped SnS 2 monolayer is energetically stable, and the estimated Curie temperature agrees well with the results of our experiment. The results suggest that Fe-doped SnS 2 has significant potential in future nanoelectronic, magnetic, and optoelectronic applications. 2D materials can be doped with magnetic atoms in order to boost their potential applications in spintronics. Here, the authors fabricate Fe-doped SnS 2 monolayers and show that Fe 0.021 Sn 0.979 S 2 exhibits ferromagnetic behaviour with perpendicular anisotropy at 2 K, and a Curie temperature of 31 K.

We employ a squeeze operator transformation approach to solve the anisotropic quantum Rabi model that includes a diamagnetic term. By carefully adjusting the amplitude of the diamagnetic term, we demonstrate that the anisotropic Rabi model with the \\(A^2\\) term can be exactly reduced to either a Jaynes-Cummings or an anti-Jaynes-Cummings model without requiring any approximations.