Ma Xucun
Chinese Academy of Sciences
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Featured researches published by Ma Xucun.
Chinese Physics Letters | 2001
Xu Ningsheng; Chen Yue; Deng Shaozhi; Chen Jun; Ma Xucun; Wang Enge
Aligned carbon nanotube (CNT) films exhibit excellent electron emission properties at very low fields. This has been attributed to the high aspect ratio of CNTs, i.e. their emitting surface can have high local field due to geometrical enhancement. It is found that a new mechanism can be responsible for the enhancement of the local field on the emitting surface of CNTs. This results from the space charge in the vacuum gap, which is readily generated due to the high emission current density of CNTs. Details are given of both experimental and theoretical studies of this effect. The mechanism also accounts for the distinct nonlinearity in Fowler-Nordheim plots often observed with CNTs. The implication of the technical application of our findings is also included.
Chinese Physics Letters | 2010
Ji Shuaihua; Fu Ying-Shuang; Zhang Tong; Chen Xi; Jia Jin-Feng; Xue Qikun; Ma Xucun
The Kondo effect in two-dimensional manganese phthalocyanine (MnPc) self-assembled monolayer films on Pb(111) islands is studied by low-temperature scanning tunneling microscopy. Variation of the Kondo temperature from 50 K to 300 K at different molecule adsorption sites is revealed. It is shown that the variation is mainly due to the change in the width of d orbital, rather than the shift of its energy. The two-dimensional dI/dV mapping reveals the periodic modulation of the Kondo resonance in the self-assembled MnPc monolayer.
Chinese Physics Letters | 2009
Jiang Peng; Wang Lili; Ning Yan-Xiao; Qi Yun; Ma Xucun; Jia Jin-Feng; Xue Qikun
We report on a two-step method for oxidation of Pb(111) surfaces, which consists of low temperature (90K) adsorption of O2 and subsequent annealing to room temperature. In situ scanning tunnelling microscopy observation reveals that oxidation of Pb(111) can occur effectively by this method, while direct room temperature adsorption results in no oxidation. Temperature-dependent adsorption behaviour suggests the existence of a precursor state for O2 adsorption on Pb(111) surfaces and can explain the oxidation-resistance of clean Pb(111) surface at room temperature.
Chinese Physics Letters | 2010
Fu Ying-Shuang; Ji Shuaihua; Zhang Tong; Chen Xi; Jia Jin-Feng; Xue Qikun; Ma Xucun
We demonstrate the importance of interface modification on improving electron confinement by preparing Pb quantum islands on Si(111) substrates with two different surface reconstructions, i.e., Si(111)-7 × 7 and Si(111)-Root3 × Root3-Pb (hereafter, 7 × 7 and R3). Characterization with scanning tunneling microscopy/spectroscopy shows that growing Pb films directly on a 7 × 7 surface will generate many interface defects, which makes the lifetime of quantum well states (QWSs) strongly dependent on surface locations. On the other hand, QWSs in Pb films on an R3 surface are well defined with small variations in linewidth on different surface locations and are much sharper than those on the 7 × 7 surface. We show that the enhancement in quantum confinement is primarily due to the reduced electron-defect scattering at the interface.
Chinese Physics Letters | 2010
Li Qing; Shiro Yamazaki; Toyoaki Eguchi; Ma Xucun; Jia Jin-Feng; Xue Qikun; Yukio Hasegawa
Self-assembly of TBrPP-Co molecules on a Si(111)-√3 × √3 Ag substrate is studied by low-temperature scanning tunneling microscopy. With the same adsorbed amount (0.07 ML), the molecules deposited by low-temperature evaporation show three kinds of ordered structures whereas those deposited by high-temperature evaporation have size-dependent ordered structures. The distinct differences in the self-assembly structures and in the electron density of states inside the molecule near the Fermi energy demonstrate that the Br atoms of the molecule desorb at the higher evaporation temperature.
Frontiers of Physics in China | 2006
Zhang Yanfeng; Li Shao-chun; Ma Xucun; Jia Jin-Feng; Xue Qi-Kun
This paper summarizes our recent work on the study of quantum size effects (QSE) and novel physical properties of the Pb/Si (111) heterostructure. Two different types of samples were investigated. One is wedge-shaped Pb islands, and the other is atomically flat Pb thin films. With scanning tunneling microscopy (STM) manipulation, we observed an intriguing morphology dynamics of the islands that swings between two extreme energy states, like that in a classical pendulum. We show that the dynamics is a result of the competition between the QSE and the classical step free energy minimizing effect. For the second type of the samples, the QSE is studied in terms of thickness-dependent film stability, electronic structure and physical properties by using STM, angle-resolved photoemission spectroscopy (ARPES) and transport measurement. The results consistently reveal the formation of quantum well states (QWS) due to electron confinement in the films. This size effect could greatly modify the electronic structure near the Fermi level and lead to quantum oscillations in superconductivity, electron-phonon coupling and thermal expansion. The work unambiguously demonstrates the possibility of quantum engineering of physical properties of thin films by exploiting well-controlled and thickness-dependent QSE.
Archive | 2015
Xue Qikun; He Ke; Ma Xucun; Chen Xi; Wang Lili; Wang Yayu; Lv Li; Chang Cuizu; Feng Xiao
Archive | 2015
Xue Qikun; He Ke; Ma Xucun; Chen Xi; Wang Lili; Chang Cuizu; Feng Xiao; Li Yao-Yi; Jia Jin-Feng
Archive | 2013
Xue Qikun; Ma Xucun; Wang Lili; Chen Xi; Jia Jin-Feng; He Ke; Ji Shuaihua; Zhang Wenhao; Wang Qingyan; Li Zhi
Chinese Physics Letters | 2010
Wu Rui; Wang Lili; Zhang Yi; Ma Xucun; Jia Jin-Feng; Xue Qi-Kun