Strain-induced effects in the electronic and spin properties of a monolayer of ferromagnetic GdAg₂

Abstract

We report on the structural, electronic and magnetic properties of a monolayer of GdAg, forming a moiré pattern on Ag(111). Combining scanning tunneling microscopy and ab initio spin-polarized calculations, we show that the electronic band structure can be shifted linearly via thermal controlled strain of the intra-layer atomic distance in the range of 1-7%, leading to lateral hetero-structuring. Furthermore, the coupling of the incommensurable GdAg alloy layer to the Ag(111) substrate leads to spatially varying atomic relaxation causing subsurface layer buckling, texturing of the electronic and spin properties, and inhomogeneity of the magnetic anisotropy energy across the layer. These results provide perspectives for control of electronic properties and magnetic ordering in atomically-thin layers.

Influence of 4f filling on electronic and magnetic properties of rare earth-Au surface compounds

“…Rare-earth/noble-metal (RE-NM) monolayer-thick, surface compounds can be readily synthesized by low-temperature vapor epitaxy on the (111) surface of Cu, Ag, and Au single crystals, leading to a rich family of surface compounds [1][2][3][4][5][6] . They all share a common, well-defined structure and excellent crystal quality with a RE-NM 2 stoichiometry, as a well as a hexagonal moiré with a nanoscale periodicity that is induced by the lattice mismatch between the RE-NM 2 monolayer and the noble metal substrate.…”

Two-Dimensional Rare Earth–Gold Intermetallic Compounds on Au(111) by Surface Alloying

“…9,10 The lattice mismatches in these systems results in periodically modulated moiré structures, leading to electronic modulations in these systems. 11,12 The structurally robust moiré lattices in GdAu2 has been reported as templates for well-aligned organic nanowires, 6 and dense arrays of Co nanodots. [13][14][15] In addition, two-dimensional ferromagnetic orders have been reported in these systems mainly originated from the 4f electrons in the rare earth atoms.…”

Exchange Splitting of a Hybrid Surface State and Ferromagnetic Order in a 2D Surface Alloy

“…This large unit cell (A = 46.24 Å B = 46.24 Å) of the superstructure can be attributed to the periodicity of the Moiré pattern of the binary Dy-Ag structure which is caused by the lattice mismatch between the Dy-Ag surface alloy and the Ag(111) surface grid. We believe that these exceptional structural properties of the DyAg 2 surface alloy are the result of a non-uniform lattice strain in the adsorbate system due to the size mismatch between the Dy and Ag atoms 15,16 .…”

“…So far, however, the concept of band structure engineering by surface alloying has mainly been limited to non-magnetic systems and has not been explored for ferromagnetic surface alloys. This is mainly due to the fact that the existence of long-range magnetic order was only recently demonstrated for 2D surface alloys consisting of the rare-earth material gadolinium (Gd) and the noble metals Ag and Au 15,16 . While Ormaza et al 15 were able to reveal the Curie temperature as well as the direction of the magnetic anisotropy axis in both systems, the spindependent electronic band structure in the ferromagnetic phase of 2D surface alloys is still elusive.…”