Haoyi Tan - Academia.edu (original) (raw)

Papers by Haoyi Tan

Novel 2D ferromagnets with high Curie temperature and large perpendicular magnetic anisotropy are... more Novel 2D ferromagnets with high Curie temperature and large perpendicular magnetic anisotropy are especially attractive owing to the future promising application in modern spintronics, but meanwhile the 2D ferromagnetic materials with high Curie temperature and large perpendicular magnetic anisotropy are rarely reported. Based on density functional theory (DFT) calculations, we predict a new kind of 2D ferromagnetic materials-GdB2N2, which possesses large magnetic moment (~7.87 μB/f.u.), high Curie temperature (~335 K) and large perpendicular magnetic anisotropy (~10.38 meV/f.u.). Biaxial strain ranging from-0.5% to 5% and different concentrations of charge-carrier doping (≤0.5 e/h per f.u.) are applied to reveal the influence on the Curie temperature and magnetic anisotropy energy (MAE). Besides, magnetic coupling process within GdB 2 N 2 is found to be via a Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism. In summary, our work here predicts a novel 2D rare-earth material GdB 2 N 2 , which not only enriches the category of 2D room-temperature ferromagnets, but also proposes a new possibility of combining traditional 2D materials and rare-earth materials to achieve more intriguing magnetic properties, finally it carves out the path for the next-generation spintronic devices and sensors.

Materials Today Physics

Physical Chemistry Chemical Physics, Nov 3, 2021

Europium, one of the rare earth elements, exhibits +2 and +3 valence states and has been widely u... more Europium, one of the rare earth elements, exhibits +2 and +3 valence states and has been widely used for magnetic modification of materials. Based on density functional theory calculations, we predict the 2D EuBr/graphene heterojunctions to exhibit metallicity, huge intrinsic-ferromagnetism nearly 7.0 μ B per Eu and the special monovalent Eu ions. Electron localization function (ELF), difference charge densities and Bader charge analyses 2 demonstrate that there are cation-π interactions between the EuBr films and graphene, which explains the stability of these unusual heterojunctions. Graphene works as substrate to enhance the stability of EuBr monolayer crystals where EuBr plays an important role to imprint ferromagnetism and enhance metallicity in the heterojunctions. Monte Carlo simulations are used to estimate a Curie temperature of about 7 K, which, together with magnetic configurations, can be further modulated by external strains and charge-carrier doping. In general, our theoretical work predicts the properties of the novel 2D ferromagnetic EuBr/graphene heterojunctions, suggests the possibility of combining the 2D intrinsicferromagnetic metal halide crystals and graphene, and opens up a new perspective in nextgeneration electronic, spintronic devices and high-performance sensors.

Journal of Physics: Condensed Matter, 2020

Despite the compositional analogue to Fe71B17(NbYZr)12 metallic glass, the Fe71B17Y12 metallic gl... more Despite the compositional analogue to Fe71B17(NbYZr)12 metallic glass, the Fe71B17Y12 metallic glass has a saturated magnetization of Ca 108 emu g−1, more than 5 times of that in Fe71B17(NbYZr)12 (20 emu g−1). The structural origin for such significant difference in magnetic performance was investigated by x-ray absorption fine structure spectra and ab initio molecular dynamics (AIMD) simulations including simulated pair-correlation function (PCF) and Voronoi tessellation. Based on the Heisenberg model of magnetism, the narrow distribution of Fe–Fe bonds with larger distances accounts for a large Fe moment of 2.0 μ B in Fe71B17Y12, while the broad distribution of Fe–Fe bonds leads to ferrimagnetic couplings which result in the small net Fe moment of 0.45 μ B in Fe71B17(NbYZr)12. This work emphasizes how the substitution of analogous 4d transition metals induces a significantly different magnetism, which sheds lights on the development of new magnetic metallic glasses with both a pro...

AOPC 2019: Optical Spectroscopy and Imaging, 2019

In the past decade, since the discovery of graphene by Geim and Novoselov, a tremendous research ... more In the past decade, since the discovery of graphene by Geim and Novoselov, a tremendous research effort has been devoted to graphene and other two-dimensional materials due to their fascinating properties. Interestingly, recent results found that ABC stacking in FLG can be controllably and locally turned into ABA stacking by illuminating the ABC region with a train of laser pulses of 790 nm wavelength, which can be visualized by TEM in dark field mode. The graphene-based terahertz devices will be reviewed in Section 2 first, including the fabrication of graphene THz modulators and then two interesting different approaches that enable the ABC stacking in FLG to be controllably and locally turned into ABA stacking are further discussed and analyzed, when both stacking occur in the same FLG device. On the other hand, MXene with ultra-thin atomic layer thickness exhibits abundant physical and chemical properties. With outstanding energy conversion efficiency, light-to-heat conversion of MXene has gained renewed research interest in the recent researches and found itself in energy and medical applications. Thus, to utilize Mxene for beneficial usage, the fabrication and relevant experimental results of MXene will be discussed and overviewed in Section 3, which would cover the stability and degradation, energy dissipation process, near-infrared light absorption of MXene. Finally, it is concluded that both heat and light conditions could significantly promote the degradation of MXene in aqueous solution, which provides guideline for fundamental study and future biomedicine delivery applications.

Microsystems & Nanoengineering, 2021

The development of flexible capacitive pressure sensors has wide application prospects in the fie... more The development of flexible capacitive pressure sensors has wide application prospects in the fields of electronic skin and intelligent wearable electronic devices, but it is still a great challenge to fabricate capacitive sensors with high sensitivity. Few reports have considered the use of interdigital electrode structures to improve the sensitivity of capacitive pressure sensors. In this work, a new strategy for the fabrication of a high-performance capacitive flexible pressure sensor based on MXene/polyvinylpyrrolidone (PVP) by an interdigital electrode is reported. By increasing the number of interdigital electrodes and selecting the appropriate dielectric layer, the sensitivity of the capacitive sensor can be improved. The capacitive sensor based on MXene/PVP here has a high sensitivity (~1.25 kPa−1), low detection limit (~0.6 Pa), wide sensing range (up to 294 kPa), fast response and recovery times (~30/15 ms) and mechanical stability of 10000 cycles. The presented sensor her...