Correlations in the elastic Landau level of spontaneously buckled graphene

Abstract

Electronic correlations stemming from nearly flat bands in van der Waals materials have demonstrated to be a powerful playground to engineer artificial quantum matter, including superconductors, correlated insulators and topological matter. This phenomenology has been experimentally observed in a variety of twisted van der Waals materials, such as graphene and dichalcogenide multilayers. Here we show that spontaneously buckled graphene can yield a correlated state, emerging from an elastic pseudo Landau level. Our results build on top of recent experimental findings reporting that, when placed on top of hBN or NbSe2 substrates, wrinkled graphene sheets relax forming a periodic, long-range buckling pattern. The low-energy physics can be accurately described by electrons in the presence of a pseudo-axial gauge field, leading to the formation of sublattice-polarized Landau levels. Moreover, we verify that the high density of states at the zeroth Landau level leads to the formation of a periodically modulated ferrimagnetic groundstate, which can be controlled by the application of external electric fields. Our results indicate that periodically strained graphene is a versatile platform to explore emergent electronic states arising from correlated elastic Landau levels.

Boundary Modes from Periodic Magnetic and Pseudomagnetic Fields in Graphene

“…±1, and φij is the angle of the hopping vector with the x axis [11]. We observe that the bands close to E = 0 are exceptionally well valley-polarized.…”

“…(S32) is similar to the one reported in Ref. [11,12], though we have chosen a different coordinate system. This choice of δt j (r i ) respects C 3z and M x symmetries but breaks C 2z symmetry.…”

“…This has been demonstrated experimentally for a sheet of graphene contacted with NbSe 2 [9]. The properties of nearly flat bands in this system have been probed for possible correlated-electron physics [9][10][11][12][13].…”

“…1a [29][30][31]. Among the many possible choices for δt i (R j ) , we adopt the following gauge that respects all the spatial symmetries of the continuum model , [11,12]. A realization in this gauge is shown in Fig.…”

Spontaneous Valley Spirals in Magnetically Encapsulated Twisted Bilayer Graphene

“…3(b); within the low-energy model H 0 (2), they modify the valley-orbit phases ϕ 1 and ϕ 2 . This is formalized by defining the valley flux of low-energy states [46,72,73] near the energy E and at position r i as…”