Topologically protected magnetic structures provide a robust platform for low power consumption devices for computation and data storage. Examples of these structures are skyrmions, chiral domain walls, and spin spirals. Here, we use scanning electron microscopy with polarization analysis to unveil the presence of chiral counterclockwise Néel spin spirals at the surface of a bulk van der Waals ferromagnet Fe3GeTe2 (FGT) at zero magnetic field. These Néel spin spirals survive up to FGT’s Curie temperature of T C = 220 K, with little change in the periodicity p = 300 nm of the spin spiral throughout the studied temperature range. The formation of a spin spiral showing counterclockwise rotation strongly suggests the presence of a positive Dzyaloshinskii–Moriya interaction in FGT, which provides the first steps towards the understanding of the magnetic structure of FGT. Our results additionally pave the way for chiral magnetism in van der Waals materials and their heterostructures.

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General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. A systematic experimental study of Gilbert damping is performed via ferromagnetic resonance for the disordered crystalline binary 3d transition-metal alloys Ni-Co, Ni-Fe, and Co-Fe over the full range of alloy compositions. After accounting for inhomogeneous linewidth broadening, the damping shows clear evidence of both interfacial damping enhancement (by spin pumping) and radiative damping. We quantify these two extrinsic contributions and thereby determine the intrinsic damping. The comparison of the intrinsic damping to multiple theoretical calculations yields good qualitative and quantitative agreement in most cases. Furthermore, the values of the damping obtained in this study are in good agreement with a wide range of published experimental and theoretical values. Additionally, we find a compositional dependence of the spin mixing conductance.

The role of chirality is becoming more important for new applications in spintronics, especially in ultrathin magnetic films. [1][2][3][4][5][6] In magnetic racetrack applications for example, the chirality directly determines how magnetic domain walls and skyrmions interact with the spin-orbit torques. 2,3,7-10 It is therefore important to investigate the key contributing factors to this chirality. The underlying interaction that is believed to stabilize the chirality is the Dzyaloshinskii-Moriya interaction (DMI). As shown by a wealth of theoretical and experimental reports this interaction requires the breaking of inversion symmetry and originates from the interface between a heavy metal and a ferromagnet for the thin film systems investigated in this paper. 4,11 The DMI also helps to stabilize skyrmions because it favours non-collinear spin configurations, 12 which are envisaged to be used in areas ranging from magnetic racetrack memory and logic applications, to radio frequency devices and neuromorphic computing. 5,6Very recently, however, it was realized that DMI is not the only interaction that can stabilize a specific chirality. [8][9][10][13][14][15] Actually, already 40 years ago it was shown that the presence of dipolar fields leads to the formation of chiral Néel caps. 16,17 Here, the stray fields originating from magnetic domains align the spins inside the domain walls at the top of the film to form clockwise (CW) Néel walls and and at the bottom of the film to form counterclockwise (CCW) Néel walls, providing an optimized flux closure state. Dipolar interactions can often be ignored for the thin-film systems used for domain-wall studies.Because of the increase in magnetic volume and reduced coupling across the non-magnetic spacer layers this is no longer the case for the multilayer repeat systems often used to stabilize room-temperature magnetic skyrmions. [15][16][17][18][19] Both theoretical 8-10 and experimental work 8,13,14 suggests that in these multilayer repeat systems the DMI is in direct competition with the dipolar fields. Without DMI, the dipolar interactions introduce Néel caps. Including DMI, however, leads to a larger fraction of the layers being occupied by the Néel cap of the chirality favoured by the DMI. The other cap will be reduced in size and occupy fewer layers. This happens until the DMI is so large that it is no longer energetically favourable to accommodate a Néel cap not favoured by the DMI.The energetics and dynamics of both skyrmions and domain walls are affected by this competition because it determines the net chirality of the magnetic textures, which in turn influences the interaction with, for example, spin-orbit torques. 8-10 A fundamental understanding of this competition is therefore needed to properly tailor the interactions such that

, J. M. (2017). Magnetic properties of ultrathin 3d transition-metal binary alloys. I. Spin and orbital moments, anisotropy, and confirmation of Slater-Pauling behavior. Physical Review B, 95(13), [134410]. DOI: 10.1103/PhysRevB.95.134410 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. The structure and static magnetic properties-saturation magnetization, perpendicular anisotropy, spectroscopic g factor, and orbital magnetization-of thin-film 3d transition metal alloys are determined over the full range of alloy compositions via x-ray diffraction, magnetometry, and ferromagnetic resonance measurements. We determine the interfacial perpendicular magnetic anisotropy by use of samples sets with varying thickness for specific alloy concentrations. The results agree with prior published data and theoretical predictions. They provide a comprehensive compilation of the magnetic properties of thin-film Ni x Co 1−x , Ni x Fe 1−x , and Co x Fe 1−x alloys that goes well beyond the often-cited Slater-Pauling dependence of magnetic moment on alloy concentration.