Electronic correlation and magnetism in the ferromagnetic metalFe3GeTe2

Abstract

Motivated by the search for design principles of rare-earth-free strong magnets, we present a study of electronic structure and magnetic properties of the ferromagnetic metal Fe3GeTe2 within local density approximation (LDA) of the density functional theory, and its combination with dynamical mean-field theory (DMFT). For comparison to these calculations, we have measured magnetic and thermodynamic properties as well as X-ray magnetic circular dichroism and the photoemission spectrum of single crystal Fe3GeTe2. We find that the experimentally determined Sommerfeld coefficient is enhanced by an order of magnitude with respect to the LDA value. This enhancement can be partially explained by LDA+DMFT. In addition, the inclusion of dynamical electronic correlation effects provides the experimentally observed magnetic moments, and the spectral density is in better agreement with photoemission data. These results establish the importance of electronic correlations in this ferromagnet.

Wafer-scale two-dimensional ferromagnetic Fe3GeTe2 thin films grown by molecular beam epitaxy

“…Figure 2a shows the temperaturedependent resistance (R-T) data of 8 nm Fe 3 GeTe 2 on Al 2 O 3 . Consistent with the theoretical predictions, 21 with decreasing temperature the resistance decreases, showing a metallic behavior. However, upon reaching~40 K, the R-T curve exhibits an upward increase.…”

Ultrathin Scattering Spin Filter and Magnetic Tunnel Junction Implemented by Ferromagnetic 2D van der Waals Material

“…LDA predicts the magnetic moment within the range of experimental values ( m = 3.60–4.89 µ B ) 32,33. To access the validity of LDA calculations, we also test the Perdew‐Burke‐Ernzerhof (PBE) functional, and the LDA functional with Hubbard U = 4.54 eV 39. However, the obtained magnetic moments ( m = 6.32/7.16 µ B for PBE/LDA+ U , respectively) are drastically overestimated.…”

“…The discovery of Fe 3 GeTe 2 (FGT),30–36 a 2D itinerant ferromagnet with Curie temperature close to room temperature (150–220 K depending on Fe occupancy33,34,37), provides a new chance for 2D spintronics. FGT has an advantage on its metallic nature which enables the performance of both electronic spin and charge,38 and it has been proposed as a rare‐earth‐free strong magnet with electronic correlation 39. Recently, a behavior of the tunneling resistance31 and large anomalous Hall effect30 were observed in bulk FGT/hBN/FGT heterostructures.…”

Van der Waals magnets: Wonder building blocks for two‐dimensional spintronics?

“…The spin degree of freedom is in this case fully quenched by the robust ferromagnetic polarization, while the line degeneracy is protected by crystalline symmetries connecting two orbitals in two adjacent layers. Strong electron correlation effects and Kondo lattice have also been evidenced, suggesting the presence of heavy fermions and periodically seated local moments.…”