Electronic and magnetic properties of the Fe₂N monolayer film tuned by substrate symmetry

Abstract

The robust bonding between Fe and N atoms has the potential to fabricate a ferromagnetic Fe 2 N monolayer of a square lattice independently of the symmetry of the substrate. The electronic and magnetic properties tuned by the symmetry of the substrates are investigated by comparing the results of scanning tunnel microscopy and x-ray absorption spectroscopy/ magnetic circular dichroism of the square Fe 2 N monolayer on the Cu(1 1 1) substrate with that on the Cu(0 0 1) substrate. A periodic electronic modulation of the Fe 2 N monolayer on the Cu(1 1 1) substrate is induced by the stripe superlattice due to the difference of the lattice symmetry between the Fe 2 N monolayer and the Cu(1 1 1) substrate. The electronic and magnetic properties of the monolayer are largely affected by the hybridization with the Cu substrate and the Fe magnetic moment is much reduced compared to the monolayer on the Cu(0 0 1) substrate.

Iron Nitride Thin Films: Growth, Structure, and Properties

“…There are also a few reports on the MBE growth of iron nitrides on other substrates, such as Cu(001), Cu(111), , and MgAl 2 O 4 (001) . Two groups that have relied on this preparation method are particularly prominent: the group of Rodolfo Miranda, which used RF plasma source for nitriding the deposited Fe films (thickness ranging between experiments, from submonolayer to 30 nm), and the group of Fumio Komori, which uses N + ions sputtering for nitriding copper substrates, deposits iron, and anneals to form iron nitrides.…”

“…STS studies were performed for ultrathin Fe 2 N and γ′-Fe 4 N films on Cu(001) 48,132 and Cu (111). 106 The DOS near the Fermi level was found to be characterized by two main electronic states: one at approximately −0.4 V, which is common for both substrates, and one at ∼0.4 V, which appears only for Cu(001). A comparison with the substrate spectra suggests that while the former might be attributed to the electron transfer from the substrate (i.e., the state also appears for pristine copper), the latter is related to iron nitride.…”

“…This technique has superior spacial and energy resolution; however, it is highly focused on electronic states close to the Fermi level. STS studies were performed for ultrathin Fe 2 N and γ′-Fe 4 N films on Cu(001) , and Cu(111) . The DOS near the Fermi level was found to be characterized by two main electronic states: one at approximately −0.4 V, which is common for both substrates, and one at ∼0.4 V, which appears only for Cu(001).…”

“…The combination of a hexagonal substrate and square film results in the formation of a Moiré superstructure, which is visible on STM images. The structure has the form of parallel darker and brighter stripes separated by approximately 1.7 nm with the atomic periodicity characteristic of γ′-Fe 4 N­(001) (Figure d). , The formation of γ′′-FeN on Cu(111) was not reported.…”

Two-dimensional chromium bismuthate: A room-temperature Ising ferromagnet with tunable magneto-optical response

“…The discovery of graphene and its atom-thick analogues with unique electronic properties has attracted a great interest to two-dimensional (2D) materials [1][2][3][4]. Recent experimental observation of magnetic order in 2D van der Waals crystals [5][6][7][8][9][10][11] was encouraging from both fundamental and practical points of view. In practice, 2D magnets offer exceptional tunability by means of applied voltage [12][13][14][15], mechanical strain [16][17][18][19], stacking [5][6][7][20][21][22], and can be used as electrodes for prospective spintronic and magnetoresistance nanodevices [23][24][25].…”