arXiv subjects

Han-Yu Wang

Publications and source records attributed to Han-Yu Wang.

5 recordsLinked to original sources

arXiv2025

Evolution of correlated electronic states of La2NiO4 under hydrostatic pressure

We elucidate the electronic structure and quantum many-body instabilities of the monolayer nickelate La2NiO4 under hydrostatic pressure using a combination of density functional theory, dynamical mean-field theory (DFT+DMFT), and random phase approximation (RPA). Our DFT+DMFT calculations reveal non-Fermi-liquid behavior and coherence loss near the Fermi level at low pressures, driven by strong electron correlations within the Ni-e_g orbital manifold, which is analogous to the low-energy electronic properties observed in La3Ni2O7. However, multi-orbital spin susceptibility analysis demonstrates an exceptionally suppressed critical Stoner parameter U_c (about 0.4~0.7 eV), indicating robust magnetic order that dominates the ground state and precludes superconductivity in the pristine system. Below U_c, superconducting instabilities exhibit a pressure-driven symmetry transition: the d_(x2-y2)-wave pairing prevails at ambient and low pressure, while the s+g-wave symmetry occurs above 75 GPa. This transition is attributed to pressure-induced self-doping effect. The high-angular-momentum g-wave component incurs significant energetic penalties, rendering high-Tc superconductivity unlikely. We conclude that the absence of superconductivity in La2NiO4 arises from its robust intrinsic magnetism and the unfavorable pairing symmetry under pressure, suggesting that alternative routes-such as chemical doping or epitaxial strain-are necessary to suppress magnetism and unlock superconducting states.

cond-mat.str-el↗

arXiv2025

Pressure and doping control of magnetic order and metallization in Ruddlesden-Popper La2NiO4

The discovery of superconductivity in multilayer nickelates under pressure has intensified interest in understanding the magnetic and electronic properties of Ruddlesden-Popper nickelates. Using density functional theory with Hubbard corrections, we investigate the magnetic ground state, electronic structure evolution under pressure, and Sr-doping effects in La$_2$NiO$_4$. We find that at ambient pressure, tetragonal La$_2$NiO$_4$ exhibits G-type antiferromagnetic order with negligible interlayer magnetic coupling. Under hydrostatic pressure, the system undergoes a continuous insulator-metal transition at ~50 GPa while maintaining robust magnetic order up to 75 GPa, contrasting sharply with the rapid magnetic suppression in La$_3$Ni$_2$O$_7$. Sr doping induces a systematic evolution from G-type to A-type, to striped antiferromagnetic orders, and eventually to ferromagnetic order, accompanied by metallization. Furthermore, LaSrNiO$_4$ displays weak charge and orbital orders. These results reveal the unique pressure and doping effects of single-layer nickelates and provide insights into the magnetic mechanisms underlying nickelate superconductivity.

cond-mat.supr-con↗

arXiv2024

Anomalous Phonon in Charge-Density-Wave Phase of Kagome Metal CsV3Sb5

CsV3Sb5, a notable compound within the kagome family, is renowned for its topological and superconducting properties, as well as its detection of local magnetic field and anomalous Hall effect in experiments. However, the origin of this local magnetic field is still veiled. In this study, we employ the first-principles calculations to investigate the atomic vibration in both the pristine and the charge-density-wave phases of CsV$_3$Sb$_5$. Our analysis reveals the presence of ``anomalous phonons" in these structures, these phonon induce the circular vibration of atoms, contributing to the phonon magnetic moments and subsequently to the observed the local magnetic fields. Additionally, we observe that lattice distortion in the charge-density-wave phase amplifies these circular vibrations, resulting in a stronger local magnetic field, particularly from the vanadium atoms. This investigation not only reveals the potential relation between lattice distortion and atomic polarization but also offers a novel idea to understand the origin of local magnetic moment in CsV3Sb5.

cond-mat.mtrl-sci↗

arXiv2023

Possible high-temperature magnetically topological material Mn$_{3}$Bi$_{2}$Te$_{6}$

The Mn-Bi-Te family displaying magnetism and non-trivial topological properties has received extensive attention. Here, we predict that the antiferromagnetic structure of Mn$_{3}$Bi$_{2}$Te$_{6}$ with three MnTe layers is energetically stable and the magnetic coupling strength of Mn-Mn is enhanced four times compared with that in the single MnTe layer of MnBi$_{2}$Te$_{4}$. The predicted N\'eel transition point is higher than 77 K, the liquid-nitrogen temperature. The topological properties show that with the variation of the MnTe layer from a single layer to three layers, the system transforms from a nontrivial topological phase to a trivial topological phase. Interestingly, the ferromagnetic state of Mn$_{3}$Bi$_{2}$Te$_{6}$ is a topological semimetal and it exhibits a topological transition from trivial to nontrivial induced by the magnetic transition. Our results enrich the Mn-Bi-Te family system, offer a new platform for studying topological phase transitions, and pave a new way to improve the working temperature of magnetically topological devices.

cond-mat.str-el↗

arXiv2022

Effective minimal model and unconventional spin-singlet pairing in Kagome superconductor CsV3Sb5

Recently synthesized Kagome compounds AV$_3$Sb$_5$ attract great attention due to the unusual coexistence of the topology, charge density wave and superconductivity. In this {\it Letter}, based on the band structures for CsV$_3$Sb$_5$ in pristine phase, we fit an effective 6-band model for the low-energy processes; utilizing the random phase approximation (RPA) on the effective minimal model, we obtain the momentum-resolved static spin susceptibility attributing the spin-fluctuation pairing mechanism, we find that the superconducting pairing strengths increase with the lift of the Coulomb correlation, and the superconductive pairing symmetry is singlet, the gap functions are antisymmetric with respect to the x-axis and the y-axis in the intermediate to strong Coulomb correlated regime,indicating the unconventional superconductivity in Kagome compounds AV$_3$Sb$_5$.

cond-mat.supr-con↗