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Nanoscale superconductivity of ?-Ga islands grown by molecular beam epitaxy

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Science China(Physics,Mechanics & Astronomy) 2015年第10期58卷 89-93页

作者： ZHANG HuiMin PENG JunPing GUAN JiaQi LI Zhi SONG CanLi WANG LiLi HE Ke MA XuCun xue qikun Institute of Physics Chinese Academy of Sciences State Key Laboratory of Low-Dimensional Quantum Physics Department of Physics Tsinghua University Collaborative Innovation Center for Quantum Matter

We report on the preparation and superconductivity of metastable γ-Ga islands on Si(111) substrate. The Ga grows in a typical Volmer-Weber mode at a low temperature of 110 K, resulting in formation of Ga nanoislands at various sizes with the identical γ-phase. In-situ low temperature scanning tunneling spectra reveal quantized electronic states in ultrathin Ga islands. It is found that both the lateral size and thickness of the Ga islands strongly suppress the superconductivity. Due to substantial surface energy contribution, the transition temperature Tc scales inversely with the island thickness and the minimum thickness for the occurrence of superconductivity is calculated to be two monolayers.

关键词： γ-Ga superconductivity size effects molecular beam epitaxy

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陶瓷也能像金属一样塑性变形?

科学通报 2023年第2期68卷 140-141页

作者：薛其坤南方科技大学深圳518055 清华大学物理系北京100084

陶瓷是我国的重大发明,是中华文明的重要载体.先进陶瓷材料因具有耐高温、耐腐蚀、强度高、密度低等优异性能,被广泛用于航空航天、能源、医疗等领域.例如,在航空发动机领域,相对于金属发动机,陶瓷发动机具有重量轻、工作温度高、热机... 详细信息

陶瓷是我国的重大发明,是中华文明的重要载体.先进陶瓷材料因具有耐高温、耐腐蚀、强度高、密度低等优异性能,被广泛用于航空航天、能源、医疗等领域.例如,在航空发动机领域,相对于金属发动机,陶瓷发动机具有重量轻、工作温度高、热机转化效率高的特点,有望大幅提升发动机的性能,因此,陶瓷发动机是科学家几个世纪以来的梦想.

关键词：陶瓷发动机先进陶瓷材料航空航天转化效率航空发动机塑性变形耐腐蚀工作温度

In situ Raman spectroscopy of topological insulator Bi2Te3 films with varying thickness

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Nano Research 2013年第9期6卷 688-692页

作者： Chunxiao Wang Xiegang Zhu Louis Nilsson Jing Wen GuangWang Xinyan Shan Qing Zhang Shulin Zhang Jinfeng Jia qikun xue State Key Laboratory for Low-Dimensional Quantum Physics Department of Physics Tsinghua University Beijing 100084 China DepartmentofPhysics Peking University Beijing 100871 China Department of Physics andAstronomy and Interdisciplinary Nanoscience Center Aarhus University 8000 Aarhus C Denmark Department of Physics Shanghai Jiaotong University Shanghai200240 China

Topological insulators （TIs） are a new state of quantum matter with a band gap in bulk and conducting surface states. In this work, the Raman spectra of topological insulator Bi2Te3 films prepared by molecular beam epitaxy （MBE） have been measured by an in situ ultrahigh vacuum （UHV）-MBE-Raman spectroscopy system. When the thickness of Bi2Te3 films decreases from 40 quintuple-layers （QL） to 1 QL, the spectral characteristics of some Raman modes appearing in bulk Bi2Te3 vary and a new vibrational mode appears, which has not been reported in previous studies and might be related to quantum size effects and symmetry breaking. In addition, an obvious change was observed at 3 QL when a Dirac cone formed. These results offer some new information about the novel quantum states of TIs.

关键词： topological insulator in situ Raman spectroscop^surface phonon mode thin film

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拓扑量子材料与量子反常霍尔效应

材料研究学报 2015年第3期29卷 161-177页

作者：何珂薛其坤清华大学物理系低维量子物理国家重点实验室北京100084

简要综述自从2005年前后发展起来的一类新的材料体系-"拓扑"量子材料,它包含拓扑绝缘体、拓扑晶体绝缘体、拓扑超导体和拓扑半金属等。这类材料中较强的自旋轨道耦合作用导致了包括量子反常霍尔效应在内的丰富多彩的量子现象,有可能对... 详细信息

简要综述自从2005年前后发展起来的一类新的材料体系-"拓扑"量子材料,它包含拓扑绝缘体、拓扑晶体绝缘体、拓扑超导体和拓扑半金属等。这类材料中较强的自旋轨道耦合作用导致了包括量子反常霍尔效应在内的丰富多彩的量子现象,有可能对未来低能耗电子学、拓扑量子计算和清洁能源等技术的发展具有重大的推动作用。

关键词：综述拓扑绝缘体量子霍尔效应量子反常霍尔效应

Atomically Smooth Ultrathin Films of Topological Insulator Sb_(2)Te_(3)

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Nano Research 2010年第12期3卷 874-880页

作者： Guang Wang Xiegang Zhu Jing Wen Xi Chen Ke He Lili Wang Xucun Ma Ying Liu Xi Dai Zhong Fang Jinfeng Jia qikun xue Key Lab for Atomic Molecular and NanoscienceDepartment of PhysicsTsinghua UniversityBeijing 100084China Institute of Physics the Chinese Academy of SciencesBeijing 100190China Department of Physics The Pennsylvania State UniversityPennsylvania 16802USA Department of Physics Shanghai Jiaotong UniversityShanghai 200240China Department of Physics Zhejiang UniversityHangzhouChina

The growth and characterization of single-crystalline thin films of topological insulators(TIs)is an important step towards their possible *** in situ scanning tunneling microscopy(STM)and angle-resolved photoemission spectroscopy(ARPES),we show that moderately thick Sb_(2)Te_(3)films grown layer-by-layer by molecular beam epitaxy(MBE)on Si(111)are atomically smooth,single-crystalline,and intrinsically ***,these films were found to exhibit a robust TI electronic structure with their Fermi energy lying within the energy gap of the bulk that intersects only the Dirac cone of the surface *** Cs in situ moves the Fermi energy of the Sb_(2)Te_(3)films without changing the electronic band structure,as predicted by *** found that the TI behavior is preserved in Sb_(2)Te_(3)films down to five quintuple layers(QLs).

关键词： Topological insulator electronic structure scanning tunneling microscopy angle-resolved photoemission spectroscopy molecular beam epitaxy

认真学习贯彻党的二十大精神扎实推进新型研究型大学发展

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国家教育行政学院学报 2023年第2期302卷 3-6页

作者：薛其坤南方科技大学广东深圳518055

习近平总书记在党的二十大报告中指出,必须坚持科技是第一生产力、人才是第一资源、创新是第一动力,深入实施科教兴国战略、人才强国战略、创新驱动发展战略,开辟发展新领域新赛道,不断塑造发展新动能新优势。党的二十大报告第五部分以... 详细信息

习近平总书记在党的二十大报告中指出,必须坚持科技是第一生产力、人才是第一资源、创新是第一动力,深入实施科教兴国战略、人才强国战略、创新驱动发展战略,开辟发展新领域新赛道,不断塑造发展新动能新优势。党的二十大报告第五部分以“实施科教兴国战略,强化现代化建设人才支撑”为题,对教育、科技、人才进行了统筹安排和一体化部署。

关键词：现代化建设人才科教兴国战略研究型大学创新驱动发展战略科技是第一生产力人才强国战略统筹安排一体化

Observation of unconventional anomalous Hall effect in epitaxial CrTe thin films

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Nano Research 2018年第6期11卷 3116-3121页

作者： Dapeng Zhao Liguo Zhang Iftikhar Ahmed Malik Menghan Liao Wenqiang Cui Xinqiang Cai Cheng Zheng Luxin Li Xiaopeng Hu Ding Zhang Jinxing Zhang Xi Chen Wanjun Jiang qikun xue State Key Laboratory of Low Dimensional Quantum Physics Department of Physics Tsinghua University Beijing 100084 China Department of Physics Beijing Normal University Beijing 100875 China Collaborative Innovation Center of Quantum Matter Beijing 100084 China

We have studied the magnetic and electrical transport properties of epitaxial NiAs-type CrTe thin films grown on SrTiO3（111） substrates. Unlike rectangle hysteresis loops obtained from magnetic measurements, we have identified intriguing extra bump/dip features from anomalous Hall experiments on the films with thicknesses less than 12 nm. This observed Hall anomaly is phenomenologically consistent with the occurrence of a topological Hall effect （THE） in chiral magnets with a skyrmion phase. Furthermore, the THE contribution can be tuned by the film thickness, showing the key contribution of asymmetric interfaces in stabilizing N6el-type skyrmions. Our work demonstrates that a CrTe thin film on SrTiO3（111） substrates is a good material candidate for studying real-space topological transport.

关键词： topological Hall effect CrTe films skyrmion phase molecular beam epitaxy

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磁性拓扑绝缘体中的量子反常霍尔效应

哈尔滨工业大学学报 2020年第6期52卷 1-11页

作者：冯硝何珂薛其坤清华大学物理系北京100084 低维量子物理国家重点实验室(清华大学) 北京100084 北京量子信息科学研究院北京100193

量子反常霍尔效应是一种不需要外磁场、具有手性边缘态的量子化霍尔效应,可以用于构建其他新奇量子态和发展未来低功耗电子学器件等.该全新的量子效应于2012年首先由中国科学家在五层Cr掺杂的(Bi,Sb)2Te3拓扑绝缘体薄膜中实现.在过去七... 详细信息

量子反常霍尔效应是一种不需要外磁场、具有手性边缘态的量子化霍尔效应,可以用于构建其他新奇量子态和发展未来低功耗电子学器件等.该全新的量子效应于2012年首先由中国科学家在五层Cr掺杂的(Bi,Sb)2Te3拓扑绝缘体薄膜中实现.在过去七年间,经过大家的努力,其观测温度从最初的30 mK已经提高到2 K左右,进一步提高量子反常霍尔效应的观测温度是目前该领域主要的研究方向之一,是许多拓扑量子效应走向应用的关键因素.本文主要总结了量子反常霍尔效应研究的实验进展,特别在提高其观测温度方面的研究进展.文章包括四个部分:前两个部分分别介绍磁性掺杂和磁性近邻拓扑绝缘体体系中量子反常霍尔效应研究,第三部分介绍最新发现的内禀磁性拓扑绝缘体体系,最后一部分对设计和构造高温量子反常霍尔效应系统的原理和路线图给出一些建议和展望.

关键词：量子反常霍尔效应拓扑绝缘体铁磁绝缘体反铁磁绝缘体分子束外延

Magnetoresistance Oscillations of Ultrathin Pb Bridges

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Nano Research 2009年第9期2卷 671-677页

作者： Jian Wang Xucun Ma Shuaihua Ji Yun Qi Yingshuang Fu Aizi Jin Li Lu Changzhi Gu X.C.Xie Mingliang Tian Jinfeng Jia qikun xue Institute of Physics Chinese Academy of SciencesBeijing 100190China The Center for Nanoscale Science and Department of Physics The Pennsylvania State UniversityUniversity ParkPennsylvania 16802-6300USA Department of Physics Oklahoma State UniversityStillwaterOK 74078USA Department of Physics Tsinghua UniversityBeijing 100084China

Pb nanobridges with a thickness of less than 10 nm and a width of several hundred nm have been fabricated from single-crystalline Pb fi lms using low-temperature molecular beam epitaxy and focus ion beam microfabrication *** observed novel magnetoresistance oscillations below the superconducting transition temperature(TC)of the *** oscillations which were not seen in the crystalline Pb fi lmsmay originate from the inhomogeneity of superconductivity induced by the applied magnetic fi elds on approaching the normal state,or the degradation of fi lm quality by thermal evolution.

关键词： Pb nanobridge magnetoresistance superconductivity molecular beam epitaxy scanning tunneling microscope focus ion beam