7 results on '"Jia-Wei, Mei"'
Search Results
2. Pressure-Enhanced Ferromagnetism in Layered CrSiTe3 Flakes
- Author
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Shanmin Wang, Lianglong Huang, Cai Liu, Jia-Wei Mei, Ying Fu, Cheng Zhang, Huimin Su, Xiaolong Zou, Yue Gu, Le Wang, and Junfeng Dai
- Subjects
Condensed Matter - Materials Science ,Phase transition ,Materials science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Mechanical Engineering ,Exchange interaction ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Bioengineering ,General Chemistry ,Coercivity ,Condensed Matter Physics ,Condensed Matter::Materials Science ,Magnetization ,Hysteresis ,Ferromagnetism ,Remanence ,Condensed Matter::Superconductivity ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Curie temperature ,Condensed Matter::Strongly Correlated Electrons ,General Materials Science - Abstract
The research on van der Waals (vdW) layered ferromagnets have promoted the development of nanoscale spintronics and applications. However, low-temperature ferromagnetic properties of these materials greatly hinder their applications. Here, we report pressure-enhanced ferromagnetic behaviours in layered CrSiTe3 flakes revealed by high-pressure magnetic circular dichroism (MCD) measurement. At ambient pressure, CrSiTe3 undergoes a paramagnetic-to-ferromagnetic phase transition at 32.8 K, with a negligible hysteresis loop, indicating a soft ferromagnetic behaviour. Under 4.6 GPa pressure, the soft ferromagnet changes into hard one, signalled by a rectangular hysteretic loop with remnant magnetization at zero field. Interestingly, with further increasing pressure, the coercive field (H_c) dramatically increases from 0.02 T at 4.6 GPa to 0.17 T at 7.8 GPa, and the Curie temperature (T_c^h: the temperature for closing the hysteresis loop) also increases from ~36 K at 4.6 GPa to ~138 K at 7.8 GPa. The influences of pressure on exchange interactions are further investigated by density functional theory calculations, which reveal that the in-plane nearest-neighbor exchange interaction and magneto-crystalline anisotropy increase simultaneously as pressure increases, leading to increased H_c and T_c^h in experiments. The effective interaction between magnetic couplings and external pressure offers new opportunities for both searching room-temperature layered ferromagnets and designing pressure-sensitive magnetic functional devices.
- Published
- 2021
3. Pressure-Dependent Intermediate Magnetic Phase in Thin Fe3GeTe2 Flakes
- Author
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Runzhang Xu, Shanmin Wang, Jia-Wei Mei, Dapeng Yu, Xiaolong Zou, Le Wang, Yusheng Zhao, Junfeng Dai, Cai Liu, Heshen Wang, Zhaojun Liu, Zhan Zhang, and Huimin Su
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Condensed Matter::Materials Science ,Materials science ,Ferromagnetism ,Condensed matter physics ,Magnetic circular dichroism ,Phase (matter) ,Exchange interaction ,Curie temperature ,General Materials Science ,Physical and Theoretical Chemistry ,Coercivity ,Anisotropy ,Magnetic field - Abstract
We investigated the evolution of ferromagnetism in layered Fe3GeTe2 flakes under different pressures and temperatures using in situ magnetic circular dichroism (MCD) spectroscopy. We found that the rectangular shape of the hysteresis loop under an out-of-plane magnetic field sweep can be sustained below 7 GPa. Above that pressure, an intermediate state appears in the low-temperature region signaled by an 8-shaped skewed hysteresis loop. Meanwhile, the coercive field and Curie temperature decrease with increasing pressures, implying the decrease of the exchange interaction and the magneto-crystalline anisotropy under pressures. The intermediate phase has a labyrinthine domain structure, which is attributed to the increase of the ratio of exchange interaction to magneto-crystalline anisotropy based on Jagla's theory. Moreover, our calculations reveal a weak structural transition around 6 GPa that corresponds to a significant change in the FeI-FeI bond length, which has strong influences on magnetic interaction. Detailed analysis on exchange interaction and magneto-crystalline anisotropy with pressure shows a consistent trend with experiments.
- Published
- 2020
4. Probing the Ferromagnetism and Spin Wave Gap in VI3 by Helicity-Resolved Raman Spectroscopy
- Author
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Yifan Gao, Hugen Yan, Li Huang, Naipeng Zhang, Qiaoling Huang, Jiasheng Zhang, Jia-Wei Mei, Gaomin Li, Yuanzhen Chen, Mingyuan Huang, Xiaohua Wu, Yani Chen, Bingbing Lyu, Yue Zhao, Yujun Zhang, and Le Wang
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Quasielastic scattering ,Materials science ,Condensed matter physics ,Scattering ,Mechanical Engineering ,Magnon ,Bioengineering ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,symbols.namesake ,Ferromagnetism ,Spin wave ,symbols ,Condensed Matter::Strongly Correlated Electrons ,General Materials Science ,0210 nano-technology ,Raman spectroscopy ,Raman scattering ,Circular polarization - Abstract
Circularly polarized light carries light spin angular momentum, which may lead helicity-resolved Raman scattering to be sensitive to the electronic spin configuration in magnetic materials. Here, we demonstrate that all Raman modes in the 2D ferromagnet VI3 show different scattering intensities to left and right circularly polarized light at low temperatures, which gives direct evidence of the time-reversal symmetry breaking. By measuring the circular polarization of the dominant Raman mode with respect to the temperature and magnetic field, the ferromagnetic (FM) phase transition and hysteresis behavior can be clearly resolved. Besides the lattice excitations, quasielastic scattering is detected in the paramagnetic phase, and it gradually evolves into the acoustic magnon mode at 18.5 cm-1 in the FM state, which gives the spin wave gap that results from large magnetic anisotropy. Our findings demonstrate that helicity-resolved Raman spectroscopy is an effective tool to directly probe the ferromagnetism in 2D magnets.
- Published
- 2020
5. Topological Hall Effect in Traditional Ferromagnet Embedded with Black-Phosphorus-Like Bismuth Nanosheets
- Author
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Xiaobin Chen, Liang Zhou, Pingbo Chen, Jia-Wei Mei, Fei Ye, Xixiang Zhang, Gan Wang, Bicong Ye, Runnan Zhang, Dapeng Yu, Bin Xi, Junwei Zhang, Junshu Chen, Hongtao He, Linjing Wang, Guo-Ping Guo, and Yang Qiu
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Materials science ,Skyrmion ,chemistry.chemical_element ,02 engineering and technology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Topology ,01 natural sciences ,Magnetic susceptibility ,0104 chemical sciences ,Bismuth ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,chemistry ,Ferromagnetism ,Hall effect ,Telluride ,General Materials Science ,0210 nano-technology ,Spectroscopy ,Molecular beam epitaxy - Abstract
Topological Hall effect is an abnormal Hall response arising from the scalar spin chirality of chiral magnetic textures. Up to now, such an effect is only observed in certain special materials, but rarely in traditional ferromagnets. In this work, we have implemented the molecular beam epitaxy technique to successfully embed black-phosphorus-like bismuth nanosheets with strong spin-orbit coupling into the bulk of chromium telluride Cr2Te3, as evidenced by atomically resolved energy dispersive X-ray spectroscopy mapping. Distinctive from pristine Cr2Te3, these Bi-embedded Cr2Te3 epitaxial films exhibit not only pronounced topological Hall effects, but also magnetoresistivity anomalies and differential magnetic susceptibility plateaus. All these experimental features point to the possible emergence of magnetic skyrmions in Bi-embedded Cr2Te3, which is further supported by our numerical simulations with all input parameters obtained from the first-principle calculations. Therefore, our work demonstrates a new efficient way to induce skyrmions in ferromagnets, as well as the topological Hall effect by embedding nanosheets with strong spin-orbit couplings.
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- 2020
6. Superconductivity in Single-Quintuple-Layer Bi2Te3 Grown on Epitaxial FeTe
- Author
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Junshu Chen, Hailang Qin, Meng Zhang, Wei-Qiang Chen, Iam Keong Sou, Linjing Wang, Liang Zhou, Fei Ye, Dapeng Yu, Jia-Wei Mei, Gan Wang, Yang Qiu, Tianluo Pan, Kaige Shi, Hongtao He, Bin Guo, Bin Xi, and Bochao Xu
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Superconductivity ,Materials science ,Condensed matter physics ,Mechanical Engineering ,Nucleation ,Bioengineering ,Fermi energy ,Heterojunction ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Epitaxy ,law.invention ,Condensed Matter::Materials Science ,law ,Condensed Matter::Superconductivity ,Topological insulator ,General Materials Science ,Scanning tunneling microscope ,0210 nano-technology ,Surface states - Abstract
How an interfacial superconductivity emerges during the nucleation and epitaxy is of great importance not only for unveiling the physical insights but also for finding a feasible way to tune the superconductivity via interfacial engineering. In this work, we report the nanoscale creation of a robust and relatively homogeneous interfacial superconductivity (TC โ 13 K) on the epitaxial FeTe surface, by van der Waals epitaxy of single-quintuple-layer topological insulator Bi2Te3. Our study suggests that the superconductivity in the Bi2Te3/FeTe heterostructure is generated at the interface and that the superconductivity at the interface does not enhance or weaken with the increase of the Bi2Te3 thickness beyond 1 quintuple layer (QL). The observation of the topological surface states crossing Fermi energy in the Bi2Te3/FeTe heterostructure with the average Bi2Te3 thickness of about 20 QL provides further evidence that this heterostructure may potentially host Majorana zero modes.
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- 2020
7. Magnetic Order-Induced Polarization Anomaly of Raman Scattering in 2D Magnet CrI3
- Author
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Hugen Yan, Takashi Taniguchi, Yuanzhen Chen, Chusheng Zhang, Mingyuan Huang, Bingbing Lyu, Qihang Liu, Jia-Wei Mei, Mengyuan Jia, Xinwei Wang, Xiaohua Wu, Minghui Wu, Shixuan Zhao, Li Huang, Le Wang, Kenji Watanabe, Yue Zhao, Yujun Zhang, and Junyang Chen
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Materials science ,Phonon ,FOS: Physical sciences ,Bioengineering ,02 engineering and technology ,Induced polarization ,Condensed Matter::Materials Science ,symbols.namesake ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Antiferromagnetism ,General Materials Science ,Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Mechanical Engineering ,Materials Science (cond-mat.mtrl-sci) ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Magnetic field ,Ferromagnetism ,Magnet ,symbols ,Condensed Matter::Strongly Correlated Electrons ,0210 nano-technology ,Raman spectroscopy ,Raman scattering - Abstract
The recent discovery of 2D magnets has revealed various intriguing phenomena due to the coupling between spin and other degree of freedoms (such as helical photoluminescence, nonreciprocal SHG). Previous research on the spin-phonon coupling effect mainly focuses on the renormalization of phonon frequency. Here we demonstrate that the Raman polarization selection rules of optical phonons can be greatly modified by the magnetic ordering in 2D magnet CrI$_3$. For monolayer samples, the dominant A$\rm_{1g}$ peak shows abnormally high intensity in the cross polarization channel at low temperature, which is forbidden by the selection rule based on the lattice symmetry. While for bilayer, this peak is absent in the cross polarization channel for the layered antiferromagnetic (AFM) state and reappears when it is tuned to the ferromagnetic (FM) state by an external magnetic field. Our findings shed light on exploring the emergent magneto-optical effects in 2D magnets., Comment: 15 pages, 4 figures
- Published
- 2019
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