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weak localization of bismuth cluster-decorated graphene and its spin-orbit interaction

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Frontiers of physics 2017年第4期12卷 123-130页

作者： Jian-Lei Ge Tian-Ru Wu Ming Gao Zhan-Bin Bai Lu Cao Xue-Feng Wang Yu-Yuan Qin Feng-Qi Songi National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced Microstructures and Department o/Physics Nanjing University Nanjing 210093 China State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China School of Electronic Science and Engineering and National Laboratory of Solid State Microstructures Nanjing University Nanjing 210093 China

weak-localization （WL） measurements were performed in a Bi cluster-decorated graphene sheet. The charge concentration was kept constant, and the amplitude of the conductance correction was sup- pressed after the Bi-cluster deposition. Detailed WL data were obtained while the gate and temperature were changed. Using E. McCamfs ibrmula, the spin-relaxation time was extracted, which was found to increase with the elastic scattering time. This is attributed to the Elliott-Yafet spin relaxation and Kane-Mele type spin--orbit coupling （SOC）. The SOC strength was enhanced to 2.64 meV as a result of the first deposition. The coverage effect is discussed according to the measurement after tim second deposition.

关键词： graphene cluster deposition weak localization spin-orbit coupling

Electrostatic field effects on three-dimensional topological insulators

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Chinese Physics B 2013年第9期22卷 63-71页

作者：杨雯敏林朝镜廖剑李永庆 Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences

Three-dimensional topological insulators are a new class of quantum matter which has interesting connections to nearly all main branches of condensed matter physics. In this article, we briefly review the advances in the field effect control of chemical potential in three-dimensional topological insulators. It is essential to the observation of many exotic quantum phenomena predicted to emerge from the topological insulators and their hybrid structures with other materials. We also describe various methods for probing the surface state transport. Some challenges in experimental study of electron transport in topological insulators will also be briefly discussed.

关键词： topological insulator electron transport weak localization surface and interface

localization effect in single crystal of RuAs_(2)

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Chinese Physics B 2024年第4期33卷 195-200页

作者：易哲铠刘琪光双魁徐升岳小宇梁慧李娜周颖吴丹丹孙燕李秋菊程鹏夏天龙孙学峰王义炎 Anhui Key Laboratory of Magnetic Functional Materials and Devices Institute of Physical Science and Information TechnologyAnhui UniversityHefei 230601China Department of Physics and Key Laboratory of Strongly-Coupled Quantum Matter Physics University of Science and Technology of ChinaHefei 230026China Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials&Micro-nano Devices Renmin University of ChinaBeijing 100872China School of Optical and Electronic Information Suzhou City UniversitySuzhou 215104China School of Physics and Optoelectronic Engineering Anhui UniversityHefei 230601China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

We report the magnetotransport and thermal properties of RuAs_(2) single ***_(2) exhibits semiconductor behavior and localization *** crossover from normal state to diffusive transport in the weak localization(WL)state and then to variable range hopping(VRH)transport in the strong localization state has been *** transitions can be reflected in the measurement of resistivity and Seebeck *** magnetoresistance(NMR)emerges with the appearance of localization effect and is gradually suppressed in high magnetic *** temperature dependent phase coherence length extracted from the fittings of NMR also indicates the transition from WL to *** measurement of Hall effect reveals an anomaly of temperature dependent carrier concentration caused by localization *** findings show that RuAs_(2) is a suitable platform to study the localized state.

关键词： weak localization variable range hopping RuAs_(2) single crystal

The exceedingly strong two-dimensional ferromagnetism in biatomic layer SrRuO_(3)with a critical conduction transition

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Nano Research 2022年第8期15卷 7584-7589页

作者： Jingxian Zhang Long Cheng Hui Cao Mingrui Bao Jiyin Zhao Xuguang Liu Aidi Zhao Yongseong Choi Hua Zhou Padraic Shafer Xiaofang Zhai Department of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China Materials Science Division Argonne National LaboratoryLemontIL 60439USA Instrument Center for Physical Science University of Science and Technology of ChinaHefei 230026China X-ray Science Division Advanced Photon SourceArgonne National LaboratoryLemontIL 60439USA Advanced Light Source Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA

In recent years,few-layer or even monolayer ferromagnetic materials have drawn a great deal of attention due to the promising integration of two-dimensional(2D)magnets into next-generation spintronic *** SrRuO_(3)monolayer is a rare example of stable 2D magnetism under ambient conditions,but only weak ferromagnetism or antiferromagnetism has been *** biatomic layer SrRuO_(3)as another environmentally inert 2D magnetic system has been paid less attention *** we study both the bi-atomic layer and monolayer SrRuO_(3)in(SrRuO_(3))n/(SrTiO_(3))m(n=1,2)superlattices in which the SrTiO3 serves as a non-magnetic and insulating space *** the monolayer exhibits arguably weak ferromagnetism,we find that the bi-atomic layer exhibits exceedingly strong ferromagnetism with a Tc of 125 K and a saturation magnetization of 1.2μB/Ru,demonstrated by both superconducting quantum interference device(SQUID)magnetometry and element-specific X-ray circular ***,in the bi-atomic layer SrRuO_(3),we demonstrate that random fluctuations and orbital reconstructions inevitably occurring in the 2D limit are critical to the electrical transport,but are much less critical to the *** study demonstrates that the bi-atomic layer SrRuO_(3)is an exceedingly strong 2D ferromagnetic oxide which has great potentials for applications of ultracompact spintronic devices.

关键词： two-dimensional(2D)ferromagnetism correlated oxides SrRuO_(3) non-Fermi liquid weak localization

Low-temperature quantum transport in CVD-grown single crystal graphene

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Nano Research 2016年第6期9卷 1823-1830页

作者： Shaohua Xiang Vaidotas Miseikis Luca Planat Stefano Guiducci Stefano Roddaro Camilla Coletti Fabio Beltram Stefan Heun NEST Istituto Nanoscienze--CNR and Scuola Normale Superiore Piazza San Silvestro 12 $6127 Pisa Italy Center for Nanotechnology Innovation @NEST Istituto Italiano di Tecnologia Piazza San Silvestro 12 56127 Pisa Italy

Chemical vapor deposition （CVD） is typically used for large-scale graphene synthesis for practical applications. However, the inferior electronic properties of CVD graphene are one of the key problems to be solved. Therefore, we present a detailed study on the electronic properties of high-quality single-crystal monolayer graphene. The graphene is grown via CVD on copper, by using a cold-wall reactor, and then transferred to Si/SiO2. Our low-temperature magneto-transport data demonstrate that the characteristics of the single-crystal CVD graphene samples are superior to those of polycrystalline graphene and have a quality which is comparable to that of exfoliated graphene on Si/SiO2. The Dirac point in our best samples occurs at back-gate voltages lower than 10 V, and a maximum mobility of 11,000 cm2/（V.s） is attained. More than 12 flat and discernible half-integer quantum Hall plateaus occur under a high magnetic field on both the electron and hole sides of the Dirac point. At a low magnetic field, the magnetoresistance exhibits a weak localization peak. Using the theory of McCann et al., we obtain inelastic scattering lengths of 〉1 um, even at the charge neutrality point of the samples.

关键词： high-quality chemicalvapor deposition (CVD)-graphene low-temperaturemagnetotransport quantum Hall effect weak localization

Electronic transport properties of Co cluster-decorated graphene

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Chinese Physics B 2018年第6期27卷 81-86页

作者： Chao-Yi Cai Jian-Hao Chen International Center for Quantum Materials Peking UniversityCollaborative Innovation Center of Quantum Matte

Interactions of magnetic elements with graphene may lead to various electronic states that have potential *** report an in-situ experiment in which the quantum transport properties of graphene are measured with increasing cobalt coverage in continuous ultra-high vacuum environment. The results show that e-beam deposited cobalt forms clusters on the surface of graphene, even at low sample temperatures. Scattering of charge carriers by the absorbed cobalt clusters results in the disappearance of the Shubnikov–de Haas（Sd H） oscillations and the appearance of negative magnetoresistance（MR）which shows no sign of saturation up to an applied magnetic field of 9 T. We propose that these observations could originate from quantum interference driven by cobalt disorder and can be explained by the weak localization theory.

关键词： in situ quantum transport negative magnetoresistance weak localization

localization correction to the anomalous Hall effect in amorphous CoFeB thin films

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Chinese Physics B 2015年第2期24卷 368-371页

作者：丁进军吴少兵杨晓非朱涛 School of Optical and Electronic Information Huazhong University of Science and Technology Institute of Physics and Beijing National Laboratory for Condensed Matter Physics Chinese Academy of Sciences

An obvious weak localization correction to anomalous Hall conductance（AHC） in very thin CoFeB film is *** find that both the weak localization to AHC and the mechanism of the anomalous Hall effect are related to the CoFeB *** the film is thicker than 3 nm,the side jump mechanism dominates and the weak locaUzation to AHC *** very thin CoFeB films,both the side jump and skew scattering mechanisms contribute to the anomalous Hall effect,and the weak localization correction to AHC is observed.

关键词： nomalous Hall effect weak localization CoFeB thin films

Cathodoluminescent and electrical properties of an individual ZnO nanowire with oxygen vacancies

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Chinese Physics B 2008年第9期17卷 3444-3447页

作者：贺晓波杨天中蔡金明张晨栋郭海明时东霞申承民高鸿钧 Beijing National Laboratory of Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences

A single ZnO nanowire with intrinsic oxygen vacancies is utilized to fabricate four-contact device with focus ion beam lithography technique. Cathodoluminescent spectra indicate strong near-UV and green emission at both room temperature and low temperatures. Experimental measurement shows the temperature-dependent conductivity of the ZnO nanowire at low temperatures （below 100 K）. The further theoretical analysis confirms that weak localization plays an important role in the electrical transport, which is attributed to the surface states induced by plenty of oxygen vacancies in ZnO nanowire.

关键词： ZnO nanowire electrical transport oxygen vacancies weak localization

Spin—Dependent Scattering Effects and Dimensional Crossover in a Quasi—Two—Dimensional Disordered Electron System

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Communications in Theoretical Physics 2002年第3期37卷 359-366页

作者： YANGYong－Hong WANGYong－Gang 等 DepartmentofPhysics SoutheastUniversityNanjing210096China

Two kinds of spin-dependent scattering effects (magnetic-impurity and spin-orbit scatterings) are investigated theoretically in a quasi-two-dimensional (quasi-2D) disordered electron system. By making use of the diagrammatic techniques in perturbation theory, we have calculated the dc conductivity and magnetoresistance due to weak-localization effects, the analytical expressions of them are obtained as functions of the interlayer hopping energy and the characteristic times: elastic, inelastic, magnetic and spin-orbit scattering times. The relevant dimensional crossover behavior from 3D to 2D with decreasing the interlayer coupling is discussed, and the condition for the crossover is shown to be dependent on the aforementioned scattering times. At low temperature there exists a spin-dependent-scattering-induced dimensional crossover in this system.

关键词： disordered system weak localization magnetic scattering spin-orbit scattering dimensional crossover