Laiming Wei
University of Science and Technology of China
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Publication
Featured researches published by Laiming Wei.
Applied Physics Letters | 2014
Guanghui Cheng; Laiming Wei; Long Cheng; Haixing Liang; Xiaoqiang Zhang; Hui Li; Guolin Yu; Changgan Zeng
Proximity to functional substrates may enhance the coupling between the quantum degrees of freedom and thus develop nontrivial quantum effects in graphene. Here, we demonstrate the successful fabrication of graphene in proximity to atomically flat magnetic insulating LaMnO3 films. The insulating nature of the LaMnO3 films not only ensures the electronic transport only occur in the graphene layers but also allow them to serve as dielectric layers for gating. Transport measurements reveal anomalous behaviors, including asymmetrical longitudinal magnetoresistivity and nonlinear Hall effect. This work may pave a way toward the realization of intriguing quantum phases in graphene.
Journal of Applied Physics | 2016
Meng Lv; Reng Wang; Laiming Wei; Guolin Yu; Tie Lin; Ning Dai; Junhao Chu; David J. Lockwood
HgTe plates have been grown by vapor phase epitaxy on (111) SrTiO3 substrates with a preferred orientation in the (111) crystalline direction, as indicated by x-ray diffraction. Examination of the plates using the micro-Raman mapping shows that the HgTe plates exhibit unusual strain patterns: the Raman peaks from the transverse-optical and longitudinal-optical phonons for the thicker (central) parts of the HgTe plates are at the same frequency as that of the bulk HgTe, while the Raman peaks for the thinner parts of the HgTe plates, which surround the thicker parts and can hardly be seen in a scanning electron microscope, are significantly larger in frequency. The full width at half maximum is smaller in the thinner areas than in the thicker parts. Theoretical analysis shows that the HgTe plates on SrTiO3 substrates suffer from compressive stress, and this may be sufficient to induce the three-dimensional topological insulator behavior in HgTe.
Journal of Applied Physics | 2013
X. Z. Liu; Y. G. Xu; Guolin Yu; Laiming Wei; Tie Lin; S. L. Guo; Junhao Chu; W. Z. Zhou; Y. G. Zhang; David J. Lockwood
The magneotransport properties of a high carrier concentration and high mobility 20-nm thick In0.53Ga0.47As/In0.52Al0.48As quantum well (QW) are investigated by tilt angle dependent Shubnikov-de Haas oscillations and by weak antilocalization (WAL) in an in-plane magnetic field. The effective g-factor g* and zero field spin splitting Δ0 are extracted from tilt angle dependent beating pattern. We found that g* shows a dramatic reduction with increasing carrier density due to the increased effective band gap. Furthermore, an anomalously rapid suppression of the WAL effect with increasing in-plane magnetic field B|| is observed. This reveals that the total dephasing rate is not solely contributed by Zeeman splitting. The microroughness scattering in the QW is proposed to be another factor to cause the dephasing and thus responsible for this effect.
Nano Letters | 2018
Dongli Wang; Xiaodong Fan; Xiaoguang Li; Siyuan Dai; Laiming Wei; Wei Qin; Fei Wu; Huayang Zhang; Zeming Qi; Changgan Zeng; Zhenyu Zhang; Jian Guo Hou
Quantum mechanical effects of single particles can affect the collective plasmon behaviors substantially. In this work, the quantum control of plasmon excitation and propagation in graphene is demonstrated by adopting the variable quantum transmission of carriers at Heaviside potential steps as a tuning knob. First, the plasmon reflection is revealed to be tunable within a broad range by varying the ratio γ between the carrier energy and potential height, which originates from the quantum mechanical effect of carrier propagation at potential steps. Moreover, the plasmon excitation by free-space photos can be regulated from fully suppressed to fully launched in graphene potential wells also through adjusting γ, which defines the degrees of the carrier confinement in the potential wells. These discovered quantum plasmon effects offer a unified quantum-mechanical solution toward ultimate control of both plasmon launching and propagating, which are indispensable processes in building plasmon circuitry.
Physical Review Letters | 2017
Guanghui Cheng; Wei Qin; Meng-Hsien Lin; Laiming Wei; Xiaodong Fan; Huayang Zhang; Shangjr Gwo; Changgan Zeng; J. G. Hou; Zhenyu Zhang
The interplays between different quasiparticles in solids lay the foundation for a wide spectrum of intriguing quantum effects, yet how the collective plasmon excitations affect the quantum transport of electrons remains largely unexplored. Here we provide the first demonstration that when the electron-plasmon coupling is introduced, the quantum coherence of electrons in graphene is substantially enhanced with the quantum coherence length almost tripled. We further develop a microscopic model to interpret the striking observations, emphasizing the vital role of the graphene plasmons in suppressing electron-electron dephasing. The novel and transformative concept of plasmon-enhanced quantum coherence sheds new insight into interquasiparticle interactions, and further extends a new dimension to exploit nontrivial quantum phenomena and devices in solid systems.
Nano Letters | 2017
Long Cheng; Laiming Wei; Haixing Liang; Yuedong Yan; Guanghui Cheng; Meng Lv; Tie Lin; Tingting Kang; Guolin Yu; Junhao Chu; Zhenyu Zhang; Changgan Zeng
Spin-orbit coupling (SOC) plays a crucial role for spintronics applications. Here we present the first demonstration that the Rashba SOC at the SrTiO3-based interfaces is highly tunable by photoinduced charge doping, that is, optical gating. Such optical manipulation is nonvolatile after the removal of the illumination in contrast to conventional electrostatic gating and also erasable via a warming-cooling cycle. Moreover, the SOC evolutions tuned by illuminations with different wavelengths at various gate voltages coincide with each other in different doping regions and collectively form an upward-downward trend curve: In response to the increase of conductivity, the SOC strength first increases and then decreases, which can be attributed to the orbital hybridization of Ti 3d subbands. More strikingly, the optical manipulation is effective enough to tune the interferences of Bloch wave functions from constructive to destructive and therefore to realize a transition from weak localization to weak antilocalization. The present findings pave a way toward the exploration of photoinduced nontrivial quantum states and the design of optically controlled spintronic devices.
Applied Physics Express | 2017
Xiaoqiang Zhang; Laiming Wei; Ran Tao; Xiaodong Fan; Lijun Zhu; Long Cheng; Lin Li; Changgan Zeng
The hybrid structure of graphene and ferromagnetic insulators is an emerging platform for achieving nontrivial effects in graphene via proximal coupling. However, the deposition of ferromagnetic insulators on graphene usually degrades the graphenes mobility. Here, we develop a substantially improved technique of fabricating a high-mobility graphene device capped by ferromagnetic insulating EuS layers. The improvement of the technique includes the deposition of EuS at a low temperature (~80 K) and the adoption of a contamination-free method to fabricate electrodes. With these improvements, the mobility of graphene in proximity to EuS is enhanced to be as high as 18000–26000 cm2 V−1 s−1. The high-mobility EuS-capped graphene may be a promising candidate for the realization of nontrivial quantum states at low magnetic fields.
Physical Review B | 2015
Haixing Liang; Long Cheng; Laiming Wei; Zhenlin Luo; Guolin Yu; Changgan Zeng; Zhenyu Zhang
Physical review applied | 2016
Long Cheng; Xiaodong Fan; Laiming Wei; Juanjuan Lu; Haixing Liang; Ji Qi; Changgan Zeng
Physical Review Letters | 2018
Zhiyong Lin; Jin-Ho Choi; Qiang Zhang; Wei Qin; Seho Yi; Pengdong Wang; Lin Li; Yifan Wang; Hui Zhang; Zhe Sun; Laiming Wei; Shengbai Zhang; Tengfei Guo; Qingyou Lu; Jun-Hyung Cho; Changgan Zeng; Zhenyu Zhang