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Transient Photoconductivity in LaRhO3 Thin Film

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Chinese physics Letters 2019年第11期36卷 70-73页

作者： Zhi Meng Lei Shen Zongwei Ma Muhammad Adnan Aslam Liqiang Xu Xueli Xu Wang Zhu Long Cheng Yuecheng Bian Li Pi Chun Zhou Zhigao Sheng anhui Province key laboratory of condensed matter physics at extreme conditions High Magnetic Field LaboratoryChinese Academy of SciencesHefei 230031 University of Science and Technology of China Hefei 230026

High-quality epitaxial LaRhO3(LRO) thin films on SrTiO3(110) single-crystalline substrates are fabricated by pulsed laser deposition and their photoconductivity properties are studied. The transient photoconductivity(TPC) effect is found in this semiconductor LRO film at room temperature. The magnitude of TPC increases almost linearly with the laser power intensities and the photon energies in visible light range. Moreover, the difference in the TPC results under two airflow conditions confirms that both intrinsic photoinduced carrier accumulation and extrinsic photoinduced heating effects contribute to the magnitude of TPC effect.

关键词： temperature. conductivity transient

Weak localization in disordered spin-1 chiral fermions

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Chinese physics B 2023年第1期32卷 493-502页

作者：苗少鹏涂岱峰周建辉 anhui key laboratory of condensed matter physics at extreme conditions High Magnetic Field LaboratoryHFIPSChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China

We theoretically investigate the quantum interference theory of magnetotransport of the three-component or spin-1 chiral fermions, which possess two linear Dirac bands and a flat band. For isotropic scalar impurities, the correction of conductivity from the coherent backscatter and non-coherent backscatter contributions cancel out in the intravalley scattering, leading to a weak localization correction to the Drude conductivity from the intervalley scattering. For the anisotropic impurities, the above cancelation is removed, we find the approximative quantum interference conductivity in the weak anisotropy case. The contributions from the chiral anomaly and classical Lorentz force are also discussed. Our work reveals some intriguing and detectable transport signatures of the novel spin-1 chiral fermions.

关键词： magnetotransport weak localization chiral fermions

Unconventional Nonreciprocal Voltage Transition in Ag_(2)Te Nanobelts

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Chinese physics Letters 2023年第12期40卷 126-130页

作者：冷鹏亮曹翔宇马强艾临风张钰达张警蕾修发贤 State key laboratory of Surface physics and Department of physics Fudan UniversityShanghai 200433China anhui Province key laboratory of condensed matter physics at extreme conditions High Magnetic Field Laboratory of the Chinese Academy of SciencesHefei 230031China

Nonreciprocal effects are consistently observed in noncentrosymmetric materials due to the intrinsic symmetry breaking and in high-conductivity systems due to the extrinsic thermoelectric effect. Meanwhile, nonreciprocal charge transport is widely utilized as an effective experimental technique for detecting intrinsic unidirectional electrical contributions. Here, we show an unconventional nonreciprocal voltage transition in topological insulator Ag_(2)Te nanobelts. The nonreciprocal voltage develops from nearly zero to giant values under the applied current I_(ac) and external magnetic fields, while remaining unchanged under various current I_(dc). This unidirectional electrical contribution is further evidenced by the differential resistance(dV/dI) measurements. Furthermore, the transition possesses two-dimensional properties under a tilted magnetic field and occurs when the voltage between two electrodes exceeds a certain value. We propose a possible mechanism based on the development of edge channels in Ag_(2)Te nanobelts to interpret the phenomenon. Our results not only introduce a peculiar nonreciprocal voltage transition in topological materials but also enrich the understanding of the intrinsic mechanism that strongly affects nonreciprocal charge transport.

关键词： value reciprocal topological

Intrinsic V vacancy and large magnetoresistance in V_(1-δ)Sb_(2)single crystal

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Chinese physics B 2022年第3期31卷 475-481页

作者： Yong Zhang Xinliang Huang Jinglei Zhang Wenshuai Gao Xiangde Zhu Li Pi Institutes of Physical Science and Information Technology Anhui UniversityHefei 230601China anhui Province key laboratory of condensed matter physics at extreme conditions High Magnetic Field Laboratory of the Chinese Academy of SciencesHefei 230031China

The binary pnictide semimetals have attracted considerable attention due to their fantastic physical properties that include topological effects, negative magnetoresistance, Weyl fermions, and large non-saturation magnetoresistance. In this paper, we have successfully grown the high-quality V_(1-δ)Sb_(2) single crystals by Sb flux method and investigated their electronic transport properties. A large positive magnetoresistance that reaches 477% under a magnetic field of 12 T at T = 1.8 K was observed. Notably, the magnetoresistance showed a cusp-like feature at the low magnetic fields and such feature weakened gradually as the temperature increased, which indicated the presence of a weak antilocalization effect(WAL). In addition, based upon the experimental and theoretical band structure calculations, V_(1-δ)Sb_(2) is a research candidate for a flat band.

关键词： binary pnictide semimetals vanadium vacancy flat band weak anti-localization

Extended phase diagram of La_(1-x)Ca_(x)MnO_(3)by interfacial engineering

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Chinese physics B 2021年第12期30卷 136-141页

作者： Kexuan Zhang Lili Qu Feng Jin Guanyin Gao Enda Hua Zixun Zhang Lingfei Wang Wenbin Wu Hefei National laboratory for Physical Sciences at Microscale University of Science and Technology of ChinaHefei 230026China anhui key laboratory of condensed matter physics at extreme conditions High Magnetic Field LaboratoryHFIPSAnhuiChinese Academy of SciencesHefei 230031China

The interfacial enhanced ferromagnetism in maganite/ruthenate system is regarded as a promising path to broaden the potential of oxide-based electronic device ***,we systematically studied the physical properties of La_(1-x)Ca_(x)MnO_(3)/SrRuO_(3)superlattices and compared them with the La1-x Cax MnO_(3)thin films and bulk *** La_(1-x)Ca_(x)MnO_(3)/SrRuO_(3)superlattices exhibit significant enhancement of Curie temperature(TC)beyond the corresponding thin films and *** on these results,we constructed an extended phase diagram of La_(1-x)Ca_(x)MnO_(3)under interfacial *** considered the interfacial charge transfer and structural proximity effects as the origin of the interfaceinduced high *** structural characterizations revealed a pronounced increase of B-O-B bond angle,which could be the main driving force for the high TCin the *** work inspires a deeper understanding of the collective effects of interfacial charge transfer and structural proximity on the physical properties of oxide heterostructures.

关键词： interfacial engineering oxygen octahedral coupling charge transfer oxide superlattices

Magnetic and magnetotransport properties of layered TaCoTe_(2) single crystals

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Chinese physics B 2023年第12期32卷 524-527页

作者：梅明陈正聂勇王园园朱相德宁伟田明亮 anhui key laboratory of condensed matter physics at extreme conditions High Magnetic Field LaboratoryHFIPSAnhuiChinese Academy of SciencesHefei 230031China Department of physics University of Science and Technology of ChinaHefei 230031China School of physics Anhui UniversityHefei 230601China

We present the synthesis of TaCoTe_(2) single crystals and a systematic investigation of the physical properties of bulk crystals and thin *** crystal shows a semiconducting behavior with temperature decreasing from room temperature and turns to a metallic behavior below 38 *** the magnetic field is applied,the temperature-dependent resistivity curves show an upturn below 10 ***,we find that the TaCoTe_(2) single crystal can be easily exfoliated from the bulk crystal by the micromechanical exfoliation *** measurements suggest that the nanoflakes have properties similar to those of the bulk crystal when the thickness is lowered to 18 nm.

关键词： two-dimensional materials magnetism electronic transport nanoflakes

Current-dependent positive magnetoresistance in La_(0.8)Ba_(0.2)MnO_(3)ultrathin films

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Chinese physics B 2021年第9期30卷 513-519页

作者： Guankai Lin Haoru Wang Xuhui Cai Wei Tong Hong Zhu Department of physics University of Science and Technology of ChinaHefei 230026China anhui Province key laboratory of condensed matter physics at extreme conditions High Magnetic Field Laboratory of the Chinese Academy of SciencesHefei 230031China key laboratory of Strongly-Coupled Quantum matter physics Chinese Academy of SciencesHefei 230026China

We report an investigation into the magnetoresistance(MR)of La_(0.8)Ba_(0.2)MnO_(3)ultrathin films with various *** the 13 nm-thick film shows the commonly reported negative magnetoresistive effect,the 6 nm-and 4 nm-thick films display unconventional positive magnetoresistive(PMR)behavior under certain *** well as the dependence on the film's thickness,it has been found that the electrical resistivity and the PMR effect of the thinner films are very dependent on the test *** example,the magnetoresistive ratio of the 4 nm-thick film changes from+46%to-37%when the current is increased from 10 nA to 100 nA under 15 kOe at 40 *** addition,the two thinner films present opposite changes in electrical resistivity with respect to the test current,i.e.,the electroresistive(ER)effect,at low *** discuss the complex magnetoresistive and ER behaviors by taking account of the weak contacts at grain boundaries between ferromagnetic metallic(FMM)*** PMR effect can be attributed to the breaking of the weak contacts due to the giant magnetostriction of the FMM grains under a magnetic *** the competing effects of the conductive filament and local Joule self-heating at grain boundaries on the transport properties,the dissimilar ER effects in the two thinner films are also *** experimental findings provide an additional approach for tuning the magnetoresistive effect in manganite films.

关键词： positive magnetoresistance electroresistance Joule self-heating conductive filament

Topological quantum states of matter in iron-based superconductors:from concept to material realization

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National Science Review 2019年第2期6卷 213-226页

作者： Ning Hao Jiangping Hu anhui Province key laboratory of condensed matter physics at extreme conditions High Magnetic Field Laboratory of Chinese Academy of Sciences Beijing National laboratory for condensed matter physics and Institute of physics Chinese Academy of Sciences CAS Center of Excellence in Topological Quantum Computation and Kavli Institute of Theoretical Sciences University of Chinese Academy of Sciences Collaborative Innovation Center of Quantum matter

We review recent progress in the exploration of topological quantum states of matter in iron-based superconductors. In particular, we focus on the non-trivial topology existing in the band structures and superconducting states of iron’s 3d orbitals. The basic concepts, models, materials and experimental results are reviewed. The natural integration between topology and high-temperature superconductivity in iron-based superconductors provides great opportunities to study topological superconductivity and Majorana modes at high temperature.

关键词： iron-based superconductor topological insulator topological superconductor spin–orbit coupling

Progress and challenges in magnetic skyrmionics

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Chinese physics B 2022年第8期31卷 73-81页

作者： Haifeng Du Xiangrong Wang anhui Province key laboratory of condensed matter physics at extreme conditions High Magnetic Field LaboratoryHFIPSAnhuiChinese Academy of SciencesHefei 230031China physics Department The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina

Magnetic skyrmions are two-dimensional localized topological spin-structures characterized by the skyrmion number that measures the number of times of spins wrapping the Bloch sphere. Skyrmions behave like particles under an external stimulus and are promising information carriers. Skyrmions can exist as an isolated object as well as skyrmion condensates in crystal structures, helical/conical states, mazes or irregular stripy states with emergent electromagnetic fields. Thus,skyrmions provide a nice platform for studying fundamental physics, other than its applications in spintronics. In this perspective, we briefly review some recent progress in the field and present an outlook of the fundamental challenges in device applications.

关键词： magnetic skyrmions