Significant Dzyaloshinskii–Moriya interaction at graphene–ferromagnet interfaces due to the Rashba effect

Abstract

The possibility of utilizing the rich spin-dependent properties of graphene has attracted much attention in the pursuit of spintronics advances. The promise of high-speed and low-energy-consumption devices motivates the search for layered structures that stabilize chiral spin textures such as topologically protected skyrmions. Here we demonstrate that chiral spin textures are induced at graphene/ferromagnetic metal interfaces. Graphene is a weak spin-orbit coupling material and is generally not expected to induce a sufficient Dzyaloshinskii-Moriya interaction to affect magnetic chirality. We demonstrate that indeed graphene does induce a type of Dzyaloshinskii-Moriya interaction due to the Rashba effect. First-principles calculations and experiments using spin-polarized electron microscopy show that this graphene-induced Dzyaloshinskii-Moriya interaction can have a similar magnitude to that at interfaces with heavy metals. This work paves a path towards two-dimensional-material-based spin-orbitronics.

Graphene/Half‐Metallic Heusler Alloy: A Novel Heterostructure toward High‐Performance Graphene Spintronic Devices

“…The calculated interlayer distances are considerably larger than those at the SLG/metal interfaces with interfacial chemical bonding, and are comparable to those in graphite and other van der Waals layered materials. The incomplete magnetization due to the influence of the interfacial perpendicular magnetic anisotropy as reported for the graphene/ferromagnetic metal heterostructures [53,68,69] and/or the surface segregation by high temperature annealing [70] may play a role as a possible mechanism of the m spin decrease. It is demonstrated that, in both heterostructures with the Co-and FeGeGa-terminated interfaces, the magnetic moments m spin , m orb and thus the m total are enhanced in the 1st atomic layers of CFGG adjacent to SLG, in agreement with the enhancements in the outermost surface region (λ p ≈ 4 Å) observed by DR-XMCD spectroscopy (Figure 3c,d).…”

Single-layer graphene on epitaxial FeRh thin films

“…Interfaces of magnetic thin films with graphene offer a rich realm of functionalities that play a key role in a number of magnetic and spintronic phenomena [1][2][3][4][5][6][7][8]. Graphene plays two major roles in prospective spintronic devices: it represents an active material, exhibiting or modifying magnetic properties, and acts as a stabilizing and protective layer [9].…”

“…Regarding magnetism, modification of magnetic properties by graphene was demonstrated in enhancement of the perpendicular magnetic anisotropy [2,15] and spin reorientation transition in Co thin films [16]. Recently, chiral magnetic structures were found in ultrathin Co and Ni films due to the Dzyaloshinskii-Moriya interaction at the graphene/ferromagnet interface [3]. Graphene has also been shown to mediate interlayer exchange coupling between magnetic layers [17].…”

Thermally Activated Processes for Ferromagnet Intercalation in Graphene-Heavy Metal Interfaces

“…In particular, when Gr is coupled with a FM, a variety of fundamental and technologically relevant effects have been found, such as high spin injection efficiency [7], antiferromagnetic coupling [8], Rashba effect [5] [9], spin filtering [10], tunnel magnetoresistance [11], or enhancement of the magnetic moment perpendicular to the surface [12][13] [14]. More recently, it has been demonstrated that Gr/FM structures allow for RT stable chiral spin textures [13] [15], and preserve spins over large distances and long times [16].…”