Laboratoire National des Champs Magnétiques Intenses

Rare-earth barium copper oxide (REBCO) superconducting tapes have experienced a rapid rise in demand and production, driven largely by high-field magnet and fusion applications. With the ongoing push for higher critical current density and long-length deposition, material used and fabrication processes continue to evolve. This makes regular independent evaluation and comparison of commercial products essential. In this work, we benchmarked tapes from four of the major manufacturers, assessing their electrical (at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{77}~\text{K}$</tex-math></inline-formula>), thermal, and mechanical performance (at room temperature). In addition, two batches of THEVA conductors from different production years were compared, highlighting improvements in their overall suitability for high-field magnet applications. The results provide a statistically reliable basis for magnet coil design, improvements in joint fabrication, and the establishment of safer operation margins.

The magnetic field is an outstanding experimental tool for physics. To go beyond the conventional commercially available superconducting (SC) magnets, very large infrastructures such as the ones gathered within the European Magnetic Field Laboratory (EMFL) are necessary. The SuperEMFL project is a design study aiming at providing the European high field user community with much higher superconducting fields. This is meant to be achieved by combining high temperature superconductor (HTS) insert magnets, an emerging technology that can work in fields above 25T, with low temperature superconductor (LTS) outsert magnets, a technology limited to fields below 25 T. The project has two design magnetic field targets, 32+T and 40+T. The first design target proposed to combined a single stack of HTS pancakes in combination with a 19 T / 150 mm LTS magnet; the second either a similar arrangement at the sake of a narrower central space or a design with two nested HTS coils combined with a 15 T/ 250 mm LTS magnet. The particular choice of the project is to use no insulation but a metallic tape co-wound with the bare HTS tape. This so-called Metal as Insulation (MI) technology enables a self-protection feature of the HTS coil by allowing the electrical bypass of defects as well as better mechanical performances in a very compact winding. The use of HTS inserts introduces a change of paradigm by providing an unprecedented combination of high magnetic field and long measurement times whilst saving vast amounts of energy in operation.

This study examines the microstructural changes in copper single-turn coils (STC) subjected to intense magnetic pressure during field generation. Three coil types were analyzed: “raw coils” (undeformed reference), “intermediate field coils” (subjected to non-destructive magnetic fields), and “maximum field coils” (destroyed during high-field generation). Vickers microhardness measurements across conductor cross-sections revealed significant local variations ranging from softening to work hardening (∼135 HV0.1) depending on the position and magnetic exposure. The results exhibit good agreement between local microhardness measurements and simulated thermal-mechanical conditions, highlighting the interplay between softening effects due to exposure to high temperatures (∼2500 K) and work hardening due to extreme magnetic pressures (∼10 GPa) occurring on microsecond timescale.

Abstract High-resolution optical spectroscopy of Rb atoms in an intermediate-Zeeman magnetic field regime is performed. Magnetic fields between 0.05 T and 0.13 T are measured. We introduce a measurement approach based on three-level $$\Lambda $$ Λ systems where the open-loop frequency energy separation is determined by the applied magnetic field. Using this method an accuracy better than 100 ppm is reached in a measurement series. In parallel, on the basis of complementary measurements based on three-level V systems we obtain the first experimental value of the Landé g-factor of the first excited state for $$^{85}$$ 85 Rb, $$^{85}g_J(5P_{1/2})$$ 85 g J ( 5 P 1 / 2 ) =0.66709(7), and for $$^{87}$$ 87 Rb, $$^{87}g_J(5P_{1/2})$$ 87 g J ( 5 P 1 / 2 ) =0.6663(2). Our approach is unprecedented in the literature for Rb. Graphic abstract Experimental results for the Land´e g-factor of the first excited state of Rb

Corrigendum: ‘Excitons and trions in WSSe monolayers’ (2023 2D Mater. 10 015018), Olkowska-Pucko, Katarzyna, Blundo, Elena, Zawadzka, Natalia, Cianci, Salvatore, Vaclavkova, Diana, Kapuściński, Piotr, Jana, Dipankar, Pettinari, Giorgio, Felici, Marco, Nogajewski, Karol, Bartos, Miroslav, Watanabe, Kenji, Taniguchi, Takashi, Faugeras, Clement, Potemski, Marek, Babiński, Adam, Polimeni, Antonio, Molas, Maciej Roman

Two outstanding problems of particle physics and cosmology, namely the strong-CP problem and the nature of dark matter, can be solved with the discovery of a single new particle, the axion. The modular high magnetic field and flux hybrid magnet platform of LNCMI-Grenoble, which was recently put in operation up to 42 T, offers unique opportunities for axion/axion-like particle search using Sikivie-type haloscopes. In this paper, the focus will be on the 350–600 MHz frequency range corresponding to the 1–3 μeV axion mass range requiring a large-bore RF-cavity. It will be built by DMAG and integrated within the large-bore superconducting hybrid magnet outsert, providing a central magnetic field up to 9 T in 812 mm warm bore diameter. The progress achieved by Néel Institute in the design of the complex cryostat with its double dilution refrigerators to cooldown below 50 mK the ultra-light Cu RF-cavity of 650 mm inner diameter and the first stage of the RF measurement chain are presented. Perspectives for the targeted sensitivity, assuming less than 2-year integration time, are recalled.

We report on magnetization measurements of single crystalline Dy2Fe17 in pulsed magnetic fields up to ∼127T. To produce the fields, we used (i) a single- and (ii) a double-coil magnet generating pulses in the 10 ms range, as well as (iii) semidestructive single-turn coils creating pulses of much shorter duration, ∼5µs. We observed steplike transitions at 64.3 and 77.7 T, for fields applied along [100] and [120], respectively. We confirmed the latter transition by ultrasound-velocity measurements using the double-coil magnet. Our data allowed us to locate the orthogonality point of Dy2Fe17 at (μ0H⊥=90T, M⊥=31μB/f.u.) and determine the intersublattice exchange field, μ0Hex=215T. Published by the American Physical Society 2025

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We report the observation of Zeeman splitting in multiple spectral lines emitted by a laser-produced, magnetized plasma (1–3 × 1018 cm−3, 1–15 eV) in the context of a laboratory astrophysics experiment under a controlled magnetic field up to 20 T. Nitrogen lines (NII) in the visible range (563–574 nm) were used to diagnose the magnetic field and plasma conditions. This was performed by coupling our data with the Stark–Zeeman line-shape code PPPB. The excellent agreement between experiment and simulations paves the way for a non-intrusive experimental platform to get time-resolved measurements of the local magnetic field in laboratory plasmas.

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