Exploring two-dimensional van der Waals heavy-fermion material: Data mining theoretical approach

Abstract

The discovery of two-dimensional (2D) van der Waals (vdW) materials often provides interesting playgrounds to explore novel phenomena. One of the missing components in 2D vdW materials is the intrinsic heavy-fermion systems, which can provide an additional degree of freedom to study quantum critical point (QCP), unconventional superconductivity, and emergent phenomena in vdW heterostructures. Here, we investigate 2D vdW heavy-fermion candidates through the database of experimentally known compounds based on dynamical mean-field theory calculation combined with density functional theory (DFT+DMFT). We have found that the Kondo resonance state of CeSiI does not change upon exfoliation and can be easily controlled by strain and surface doping. Our result indicates that CeSiI is an ideal 2D vdW heavy-fermion material and the quantum critical point can be identified by external perturbations.

Two-dimensional heavy fermion in a monoatomic-layer Kondo lattice YbCu2

“…The combination of the HF state and low dimensionality modifies the ground state of the system because the order parameter of these systems is much more sensitive to dimensionality 9 , 10 . The ground state of two-dimensional (2D) HF can be easily controlled to the vicinity of a quantum critical point, which is the host to realize unconventional physical properties such as HF superconductivity, by simple external fields such as gate-tuning 11 , 12 , and surface doping 13 in addition to traditional external perturbations; temperature, pressure, and magnetic field. Fabricating artificial low-dimensional strongly correlated electron systems and quantizing a three-dimensional HF state by quantum confinement 14 are suitable methods to investigate the novel electronic phase.…”

Nature of the Unconventional Heavy-Fermion Kondo State in Monolayer CeSiI

“…DMFT calculations have been performed on CeSiI. 14 In this analysis, a conventional Kondo peak is captured for this system. To study an unconventional nodal behavior within a DMFT methodology, a local dependency in the self-energy could be included.…”

“…In the presence of Kondo hybridization, the magnetic exchange interactions promote the formation of the Kondo gap around the K points. DMFT calculations have been performed on CeSiI . In this analysis, a conventional Kondo peak is captured for this system.…”

“…The coexistence of electronic orders in two-dimensional (2D) materials establishes a rich platform for the emergence of new physics. Since the isolation of van der Waals monolayers, a variety of magnetic orders have been observed in the 2D limit, including ferromagnetic, , quantum spin-liquid candidates, , and multiferroic order. , Furthermore, exploring the unique degrees of freedom of van der Waals materials, namely, the easy and clean stacking of layers forming heterostructures and introducing twist angles between layers, has allowed the emergence of new magnetic orders, including orbital ferromagnets , and heavy-fermion Kondo lattice materials. − The recent isolation of CeSiI in the ultrathin limit establishes heavy-fermion Kondo insulators as a new member in the family of van der Waals building blocks.…”

“…In the realm of van der Waals materials, heavy-fermion systems have been artificially engineered in heterostructures with different 2D materials including 1T–1H TaS 2 bilayers, MoTe 2 /WSe 2 bilayers, and MoS 2 bilayers. ,, Now, monolayer CeSiI brings Kondo physics to a single van der Waals block, allowing us to study these systems from a novel perspective combining typical surface-science experimental techniques such as scanning tunneling microscopy and exploiting the degrees of freedom characteristic of van der Waals materials . However, theoretical studies on monolayer CeSiI are still scarce due to the difficult treatment of Kondo systems from an ab initio perspective. This obstacle hinders the study of the complex phase diagram that could arise in CeSiI van der Waals heterostructures.…”