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The discoveries of intrinsic ferromagnetism in atomically-thin van der Waals crystals have opened up a new research field enabling fundamental studies on magnetism at twodimensional (2D) limit as well as development of magnetic van der Waals heterostructures. To date, a variety of 2D ferromagnetism has been explored mainly by mechanically exfoliating 'originally ferromagnetic (FM)' van der Waals crystals, while bottom-up approach by thin film growth technique has demonstrated emergent 2D ferromagnetism in a variety of 'originally non-FM' van der Waals materials. Here we demonstrate that V5Se8 epitaxial thin films grown by molecular-beam epitaxy (MBE) exhibit emergent 2D ferromagnetism with intrinsic spin polarization of the V 3d electrons despite that the bulk counterpart is 'originally antiferromagnetic (AFM)'. Moreover, thickness-dependence measurements reveal that this newly-developed 2D ferromagnet could be classified as an itinerant 2D Heisenberg ferromagnet with weak magnetic anisotropy, broadening a lineup of 2D magnets to those potentially beneficial for future spintronics applications.KEYWORDS: 2D magnet, vanadium selenide, molecular-beam epitaxy, anomalous Hall effect,x-ray magnetic circular dichroism 3 Exploring novel 2D magnets that exhibit long-range magnetic order at the 2D limit is one of central topics in modern condensed-matter researches based on 2D materials and their heterostructures. 1-5 There, the most-frequently-used approach is to mechanically exfoliate FM van der Waals crystals down to the ultrathin regime, providing a simple but versatile route to exploration of intrinsic 2D ferromagnetism as initially demonstrated on insulating ferromagnets, Cr2Ge2Te6 (CGT) and CrI3. 1,2 Those pioneering works as well as the recent study on metallic ferromagnet, Fe3GeTe2 (FGT), 3 have experimentally verified the fundamental aspect of 2D ferromagnets at two extreme conditions; long-range FM order could be stabilized down to the monolayer limit in Ising-type ferromagnets with strong uniaxial magnetic anisotropy (i.e., CrI3 and FGT), whereas it is strongly suppressed at the 2D limit in Heisenberg-type ferromagnets with weak anisotropy (i.e., CGT) due to thermal fluctuations in accord with the Mermin-Wagner theorem. 6 However, very intriguingly, it turned out that 2D Heisenberg ferromagnets give rise to an emergent functionality enabling control of the FM transition temperature by external magnetic fields, 1 which is unique to this class of 2D ferromagnets with weak magnetic anisotropy.Apart from mechanical exfoliation, recent development of thin film growth technique has enabled us to investigate magnetic properties of a wide variety of van der Waals materials down to the monolayer limit even including hardly-cleavable and thermodynamically-metastable compounds, providing a unique and powerful path to exploration of novel 2D magnets. In fact, those atomically-thin samples grown by bottom-up approach have often provided emergent roomtemperature 2D ferromagnetism in originally non-FM compounds as demonstrate...

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The structure of the radial electric field and heat transport at the magnetic island in the Large Helical Device is investigated by measuring the radial profile of poloidal flow with charge exchange spectroscopy. The convective poloidal flow inside the island is observed when the n/m=1/1 external perturbation field becomes large enough to increase the magnetic island width above a critical value (15-20% of minor radius) in LHD. This convective poloidal flow results in a non-flat space potential inside the magnetic island. The sign of the curvature of the space potential depends on the radial electric field at the boundary of the magnetic island. The heat transport inside the magnetic island is studied with a cold pulse propagation technique. The experimental results show the existence of the radial electric field shear at the boundary of the magnetic island and a reduction of heat transport inside the magnetic island