RKKY interaction between adsorbed magnetic impurities in graphene: Symmetry and strain effects

Abstract

The growing interest in carbon-based spintronics has stimulated a number of recent theoretical studies on the RKKY interaction in graphene, with the aim of determining the most energetically favourable alignments between embedded magnetic moments. The RKKY interaction in undoped graphene decays faster than expected for conventional two-dimensional materials and recent studies suggest that the adsorption configurations favoured by many transition-metal impurities may lead to even shorter ranged decays and possible sign-changing oscillations. Here we show that these features emerge in a mathematically transparent manner when the symmetry of the configurations is included in the calculation. Furthermore, we show that by breaking the symmetry of the graphene lattice, via uniaxial strain, the decay rate, and hence the range, of the RKKY interaction can be significantly altered. Our results suggest that magnetic interactions between adsorbed impurities in graphene can be manipulated by careful strain engineering of such systems.

Prospects of spintronics based on 2D materials

“…In many of the above studies, it was found that strain is not only useful in stabilizing atoms and molecules adsorbed on the 2D materials, it is also effective in tuning the magnetic properties of these 2D materials . Besides examples already mentioned above, Xu et al found, based on first‐principles calculations, that a moderate biaxial tensile strain (4%) is able to change pristine NbSe 2 and NbS 2 from the AFM ground state to the FM state.…”

RKKY interaction between extended magnetic defect lines in graphene

“…In undoped graphene a decay rate of D −3 for substitutional, top-adsorbed, and bridge-adsorbed impurities is found, while a much faster decay rate of D −7 is found for center-adsorbed impurities. 13,14,20,23 This decay rate is faster than the D −2 decay expected for conventional two-dimensional materials and arises from the vanishing density of states at the Fermi energy in graphene. 26 This fast decay rate results in the interaction being very short ranged and any method of amplifying the coupling to extend its range could prove useful for both the experimental detection of the RKKY interaction and future spintronic applications.…”

Signatures of interfacial topological chiral modes via RKKY exchange interaction in Dirac and Weyl systems

“…In the present work, we also aim to extract the direct signatures of these ICM via Ruderman-Kittel-Kasuya-Yosida (RKKY) [30][31][32] exchange interaction between two magnetic impurities placed across the DW created in gapped graphene and in WSM with broken IS. It is an indirect exchange interaction mediated by the conduction electrons of the host material and already investigated extensively in different Dirac materials [33][34][35][36][37][38][39], topological insulators [40], etc. RKKY exchange interaction has also been proposed to determine the magnetic ordering in spin glasses [41] and alloys [42] and to probe topological phase in silicene [43], edge states of graphene nanoribbon [44] and 2D topological insulators [45], decoupled edge modes in phosphorene [46], order of tilting in the spectrum of borophene [47] and the Fermi arc in WSM thin films [48], etc.…”