Graphene is an excellent material for long distance spin transport but allows little spin manipulation. Transition metal dichalcogenides imprint their strong spin-orbit coupling into graphene via proximity effect, and it has been predicted that efficient spin-to-charge conversion due to spin Hall and Rashba-Edelstein effects could be achieved. Here, by combining Hall probes with ferromagnetic electrodes, we unambiguously demonstrate experimentally spin Hall effect in graphene induced by MoS2 proximity and for varying temperature up to room temperature. The fact that spin transport and spin Hall effect occur in different parts of the same material gives rise to a hitherto unreported efficiency for the spinto-charge voltage output. Remarkably for a single graphene/MoS2 heterostructure-based device, we evidence a superimposed spin-to-charge current conversion that can be indistinguishably associated with either the proximity-induced Rashba-Edelstein effect in graphene or the spin Hall effect in MoS2. By comparing our results to theoretical calculations, the latter scenario is found the most plausible one. Our findings pave the way towards the combination of spin information transport and spin-to-charge conversion in two-dimensional materials, opening exciting opportunities in a variety of future spintronic applications.The efficient transport and the manipulation of spins in the same material are mutually exclusive as they would require simultaneously weak and strong spin-orbit coupling (SOC) respectively. Graphene, due to its low intrinsic SOC, is proven to be an outstanding material that can transport spins over long distance of tens of micrometres 1-10 . For the same reason, the generation and tuning of spin currents in graphene are out of reach, limiting its capability to active spintronic device functionalities and related applications. To solve this issue, methods to artificially induce SOC in graphene have been explored. For instance, the SOC in graphene has been enhanced by chemical doping [11][12][13][14][15][16][17] or by proximity-induced coupling with materials possessing large SOC [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] . The latter method is more convenient since the chemical properties of graphene are not altered, whereas its high-quality electronic transport properties are preserved.Transition metal dichalcogenides (TMDs) with chemical formula MX2 (M=Mo, W and X=S, Se) are layered materials of semiconducting nature displaying unique combined electronic, optical, spintronic and valleytronic properties [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] . They possess a strong intrinsic SOC of tens of meV, few orders larger than that of pristine graphene 36,37 . Accordingly, a large intrinsic spin Hall effect (SHE) has been theoretically predicted in TMDs 38 . However, its experimental observation remains elusive because of the technical difficulties to inject and detect spin information into these materials 49,50 . Only recently, a spin-orbit torque experim...

The nucleation of reversed magnetic domains in Pt/Co/AlOx microstructures with perpendicular anisotropy was studied experimentally in the presence of an in-plane magnetic field. For large enough in-plane field, nucleation was observed preferentially at an edge of the sample normal to this field. The position at which nucleation takes place was observed to depend in a chiral way on the initial magnetization and applied field directions. A quantitative explanation of these results is proposed, based on the existence of a sizable Dzyaloshinskii-Moriya interaction in this sample. Another consequence of this interaction is that the energy of domain walls can become negative for in-plane fields smaller than the effective anisotropy field. [5]. In the latter case, the transcription of the chirality from the atomic scale to the macroscopic scale of textures may be impeded by the existence of an anisotropy. This is exemplified in liquid crystals, where under a DC magnetic or electric field that induces anisotropy, the cholestericnematic transition takes place [4]. Thus, the detection and quantification of a chiral interaction when it is too weak to give rise to a global chiral texture is difficult.Magnetism is another prominent field where chiral textures are considered. A chiral magnetic interaction indeed exists, namely an anti-symmetric exchange called Dzyaloshinskii-Moriya interaction (DMI) [5, 6], that is allowed when central symmetry is broken. In many compounds having this property, especially the cubic B20 structures with depressed magnetic anisotropy, chiral textures like homochiral spin spirals or 2D skyrmion lattices have been observed, both in reciprocal [7] and in real space [8]. Another class of chiral magnetic systems has recently appeared, namely the few atomic layer thick samples grown on an underlayer with large spinorbit interaction, showing structural inversion asymmetry and perpendicular magnetic anisotropy (PMA) [9][10][11][12]. In these systems, PMA is very strong so that chiral spin spirals are not stable, and as a result DMI has remained unnoticed for about 20 years. However, at magnetic edges like a domain wall (DW) separating two uniformly magnetized domains or at physical edges in a microstructure, the competition of chiral interaction with anisotropy is modified. Indeed, the peculiarities of field and current-induced dynamics of domain walls in such samples [13][14][15] have been found to be consistent with a chiral texture localized on the DW, deriving from the presence of interface-induced DMI [16]. These local chiral magnetization textures, that appear as Néel walls of a fixed chirality, have also been observed recently by lowenergy electron microscopy [17,18], on samples with wide domain walls.In this Letter we show that chiral interactions can also be detected at the edges of a microstructure: in the presence of an additional in-plane field, nucleation of reversed domains takes place preferentially at one edge of the sample, oriented perpendicular to this field. The side at which nucle...

Magnetization reversal by an electric current is essential for future magnetic data storage technology, such as magnetic random access memories. Typically, an electric current is injected into a pillar-shaped magnetic element, and switching relies on the transfer of spin momentum from a ferromagnetic reference layer (an approach known as spin-transfer torque). Recently, an alternative technique has emerged that uses spin-orbit torque (SOT) and allows the magnetization to be reversed without a polarizing layer by transferring angular momentum directly from the crystal lattice. With spin-orbit torque, the current is no longer applied perpendicularly, but is in the plane of the magnetic thin film. Therefore, the current flow is no longer restricted to a single direction and can have any orientation within the film plane. Here, we use Kerr microscopy to examine spin-orbit torque-driven domain wall motion in Co/AlOx wires with different shapes and orientations on top of a current-carrying Pt layer. The displacement of the domain walls is found to be highly dependent on the angle between the direction of the current and domain wall motion, and asymmetric and nonlinear with respect to the current polarity. Using these insights, devices are fabricated in which magnetization switching is determined entirely by the geometry of the device.

Structural symmetry breaking in magnetic materials is responsible for a variety of outstanding physical phenomena. Examples range from the existence of multiferroics, to current induced spin orbit torques (SOT) and the formation of topological magnetic structures. In this letter we bring into light a novel effect of the structural inversion asymmetry (SIA): a chiral damping mechanism. This phenomenon is evidenced by measuring the field driven domain wall (DW) motion in perpendicularly magnetized asymmetric Pt/Co/Pt trilayers. The difficulty in evidencing the chiral damping is that the ensuing DW dynamics exhibit identical spatial symmetry to those expected from the Dzyaloshinskii-Moriya interaction (DMI). Despite this fundamental resemblance, the two scenarios are differentiated by their time reversal properties: while DMI is a conservative effect that can be modeled by an effective field, the chiral damping is purely dissipative and has no influence on the equilibrium magnetic texture. When the DW motion is modulated by an in-plane magnetic field, it reveals the structure of the internal fields experienced by the DWs, allowing to distinguish the physical mechanism. The observation of the chiral damping, not only enriches the spectrum of physical phenomena engendered by the SIA, but since it can coexists with DMI it is essential for conceiving DW and skyrmion devices

Efficient and versatile spin-to-charge current conversion is crucial for the development of spintronic applications, which strongly rely on the ability to electrically generate and detect spin currents. In this context, the spin Hall effect has been widely studied in heavy metals with strong spinorbit coupling. While the high crystal symmetry in these materials limits the conversion to the orthogonal configuration, unusual configurations are expected in low symmetry transition metal dichalcogenide semimetals, which could add flexibility to the electrical injection and detection of pure spin currents. Here, we report the observation of spin-to-charge conversion in MoTe2 flakes, which are stacked in graphene lateral spin valves. We detect two distinct contributions arising from the conversion of two different spin orientations. In addition to the conventional conversion where the spin polarization is orthogonal to the charge current, we also detect a conversion where the spin polarization and the charge current are parallel. Both contributions, which could arise either from bulk spin Hall effect or surface Edelstein effect, show large efficiencies comparable to the best spin Hall metals and topological insulators. Our finding enables the simultaneous conversion of spin currents with any in-plane spin polarization in one single experimental configuration.Symmetry is a unifying principle that governs all aspects of Physics, from the model of atomic orbitals to the Landau theory of phase transitions. The physical properties of crystalline solids are also highly constrained by symmetry 1 and, in turn, as symmetry is progressively lowered through the 32 crystallographic point groups, novel transport effects emerge, such as the non-linear Hall effect 2 , the spin galvanic effect 3 and the valley magnetoelectricity 4 in non-centrosymmetric crystals, and the magnetochiral anisotropy 5 in chiral crystals. Crystal symmetry dictates also the geometry of a phenomenon that has attracted a lot of attention in recent years, the spin Hall effect (SHE) or its reciprocal effect [inverse SHE (ISHE)], which are generally observed in materials possessing strong spin-orbit coupling (SOC), and enables the interconversion between charge and spin currents. In conventional spin Hall materials, high crystal symmetry imposes that injecting a charge current density ( ) can only result in a transverse spin current density ( ) with a spin polarization ( ) orthogonal to both and (Figure 1a) 6 . SHE/ISHE are crucial effects for the electrical generation or detection of spin current, required in applications such as spin-orbit torque memories 7,8,9 and spin-based logic devices 10,11 . These applications would highly benefit from more versatile SHE/ISHE configurations which can be obtained by lifting the constraints imposed by high crystal symmetry and enabling unusual spin-to-charge conversion geometries in low-symmetry crystals 12,13,14 (Figures 1b,c).

The proximity effect opens ways to transfer properties from one material into another and is especially important in two-dimensional materials. In van der Waals heterostructures, transition metal dichalcogenides (TMD) can be used to enhance the spin-orbit coupling of graphene leading to the prediction of gate controllable spin-to-charge conversion (SCC). Here, we report for the first time and quantify the SHE in graphene proximitized with WSe2 up to room temperature. Unlike in other graphene/TMD devices, the sole SCC mechanism is the spin Hall effect and no Rashba-Edelstein effect is observed. Importantly, we are able to control the SCC by applying a gate voltage. The SCC shows a high efficiency, measured with an unprecedented SCC length larger than 20 nm. These results show the capability of two-dimensional materials to advance towards the implementation of novel spin-based devices and future applications.The integration of spintronic devices into existing electronic technology will strongly depend on the all-electrical control of spin currents, with a crucial role being played by the interconversion between charge currents and spin currents. The latter can be achieved by the (inverse) spin Hall effect [(I)SHE] in bulk conductors 1-3 , as well as by the (inverse) Rashba-Edelstein effect [(I)REE] in two-dimensional (2D) systems and interfaces 4 , allowing ferromagnet(FM)-free electrical generation and detection of spin currents. While the experimental observation of the (I)SHE and (I)REE have been successful in different systems 3,5,6 , the transition from the laboratory to industrial applications will require careful device design and material choice to achieve large enough signals for practical implementation [7][8][9][10] .

Controlling BiFeO3 (BFO)/ferromagnet (FM) interfacial coupling appears crucial for electrical control of spintronic devices using this multiferroic. Here, we analyse the magnetic behaviour of exchange-biased epitaxial-BiFeO3/FM bilayers with in-plane or out-of-plane magnetic anisotropies. We report bimodal distributions of blocking temperatures similar to those of polycrystalline-antiferromagnet (AF)/FM bilayers. The high-temperature contribution depends on the FM anisotropy direction and is likely related to thermally activated depinning of domain walls in the BiFeO3 single crystal film as opposed to thermally activated reversal of spins in AF grains for polycrystalline AF. In contrast, the low-temperature contribution weakly depends on the anisotropy direction, consistent with a spin-glass origin.

Spin-orbit coupling in graphene can be enhanced by chemical functionalization, adatom decoration or proximity with a van der Waals material. As it is expected that such enhancement gives rise to a sizeable spin Hall effect, a spin-to-charge current conversion phenomenon of technological relevance, it has sparked wide research interest. However, it has only been measured in graphene/transition metal dichalcogenide van der Waals heterostructures with limited scalability. Here, we experimentally demonstrate spin Hall effect up to room temperature in bilayer graphene combined with a nonmagnetic insulator, an evaporated bismuth oxide layer. The measured spin Hall effect raises most likely from an extrinsic mechanism. With a large spin-to-charge conversion efficiency, scalability, and ease of integration to electronic devices, we show a promising material heterostructure suitable for spin-based device applications.