FeSe

/Tag: FeSe

Structural evolution and phase diagram of the superconducting iron selenides $mathrm{L}{mathrm{i}}_{x}{({mathrm{C}}_{2}{mathrm{H}}_{8}{mathrm{N}}_{2})}_{y}mathrm{F}{mathrm{e}}_{2}mathrm{S}{mathrm{e}}_{2}(x=0∼0.8)$

2019-03-04T14:34:42+00:00March 4th, 2019|Categories: Publications|Tags: |

Author(s): Linlin Zhao, Da Wang, Qingzhen Huang, Hui Wu, Ruijin Sun, Xiao Fan, Yanpeng Song, Shifeng Jin, and Xiaolong ChenHere we report on the structural and electronic phase diagram of lithium and ethylenediamine intercalated FeSe in a wide range of dopant concentration (x=0∼0.8). Undoped (C2H8N2)yFe2Se2 crystallizes in an orthorhombic phase. With increasing lithium doping, an orthorhombic to tetragonal phase transit…[Phys. Rev. B 99, 094503] Published Mon Mar 04, 2019

Published in: "Physical Review B".

X-ray diffraction analysis to support phase identification in FeSe and Fe$_7$Se$_8$ epitaxial thin films. (arXiv:1901.09794v1 [cond-mat.mtrl-sci])

2019-01-29T02:29:32+00:00January 29th, 2019|Categories: Publications|Tags: |

X-ray diffraction (XRD) data and analysis for epitaxial iron selenide thin films grown by pulsed laser deposition (PLD) are presented. The films contain ${beta}$-FeSe and Fe$_7$Se$_8$ phases in a double epitaxy configuration with the ${beta}$-FeSe phase (001) oriented on the (001) MgO growth substrate. Fe$_7$Se$_8$ simultaneously takes on two different epitaxial orientations in certain growth conditions, exhibiting both (101)- and (001)- orientations. Each of these orientations are verified with the presented XRD data. Additionally, XRD data used to determine the PLD target composition as well as mosaic structure of the ${beta}$-FeSe phase are shown.

Published in: "arXiv Material Science".

Particulate Generation on Surface of Iron Selenide Films by Air Exposure. (arXiv:1901.08899v1 [cond-mat.supr-con])

2019-01-28T02:29:22+00:00January 28th, 2019|Categories: Publications|Tags: |

Nanometer-sized particular structures are generated on the surfaces of FeSe epitaxial films directly after exposure to air; this phenomenon was studied in the current work because these structures are an obstacle to field-induced superconductivity in electric double-layer transistors using FeSe channel layers. Chemical analyses using field-effect scanning Auger electron spectroscopy revealed no clear difference in the chemical composition between the particular structures and the other flat surface region. This observation limits the possible origins of the particulate formation to light elements in air such as O, C, H, and N.

Published in: "arXiv Material Science".

Insulator-like behavior coexisting with metallic electronic structure in strained FeSe thin films grown by molecular beam epitaxy

2019-01-24T14:35:05+00:00January 24th, 2019|Categories: Publications|Tags: |

Author(s): Kota Hanzawa, Yuta Yamaguchi, Yukiko Obata, Satoru Matsuishi, Hidenori Hiramatsu, Toshio Kamiya, and Hideo HosonoThis paper reports that ∼10-nm-thick iron selenide (FeSe) thin films exhibit insulator-like behavior in terms of the temperature dependence of their electrical resistivity even though bulk FeSe has a metallic electronic structure that has been confirmed by photoemission spectroscopy and first-princi…[Phys. Rev. B 99, 035148] Published Thu Jan 24, 2019

Published in: "Physical Review B".

Synergetic Behavior in 2D Layered Material/Complex Oxide Heterostructures

2019-01-01T22:34:47+00:00January 1st, 2019|Categories: Publications|Tags: , , , |

Heterostructures composed of a 2D layered material (2DLM) and complex transition metal oxides (TMO) provide a new platform for design, realization, and examination of artificial materials that are physically intriguing and technologically useful. An overview is presented for some of the examples, where various functional properties emerge at the novel 2DLM/TMO heterostructures. Abstract The marriage between a 2D layered material (2DLM) and a complex transition metal oxide (TMO) results in a variety of physical and chemical phenomena that cannot be achieved in either material alone. Interesting recent discoveries in systems such as graphene/SrTiO3, graphene/LaAlO3/SrTiO3, graphene/ferroelectric oxide, MoS2/SrTiO3, and FeSe/SrTiO3 heterostructures include voltage scaling in field‐effect transistors, charge state coupling across an interface, quantum conductance probing of the electrochemical activity, novel memory functions based on charge traps, and greatly enhanced superconductivity. In this context, various properties and functionalities appearing in numerous different 2DLM/TMO heterostructure systems are reviewed. The results imply that the multidimensional heterostructure approach based on the disparate material systems leads to an entirely new platform for the study of condensed matter physics and materials science. The heterostructures are also highly relevant technologically as each constituent material is a promising candidate for next‐generation optoelectronic devices.

Published in: "Advanced Materials".

Synergetic Behavior in 2D Layered Material/Complex Oxide Heterostructures

2018-12-29T22:35:39+00:00December 29th, 2018|Categories: Publications|Tags: , , , |

Heterostructures composed of a 2D layered material (2DLM) and complex transition metal oxides (TMO) provide a new platform for design, realization, and examination of artificial materials that are physically intriguing and technologically useful. An overview is presented for some of the examples, where various functional properties emerge at the novel 2DLM/TMO heterostructures. Abstract The marriage between a 2D layered material (2DLM) and a complex transition metal oxide (TMO) results in a variety of physical and chemical phenomena that cannot be achieved in either material alone. Interesting recent discoveries in systems such as graphene/SrTiO3, graphene/LaAlO3/SrTiO3, graphene/ferroelectric oxide, MoS2/SrTiO3, and FeSe/SrTiO3 heterostructures include voltage scaling in field‐effect transistors, charge state coupling across an interface, quantum conductance probing of the electrochemical activity, novel memory functions based on charge traps, and greatly enhanced superconductivity. In this context, various properties and functionalities appearing in numerous different 2DLM/TMO heterostructure systems are reviewed. The results imply that the multidimensional heterostructure approach based on the disparate material systems leads to an entirely new platform for the study of condensed matter physics and materials science. The heterostructures are also highly relevant technologically as each constituent material is a promising candidate for next‐generation optoelectronic devices.

Published in: "Advanced Materials".

Synergetic Behavior in 2D Layered Material/Complex Oxide Heterostructures

2018-12-28T08:34:25+00:00December 28th, 2018|Categories: Publications|Tags: , , , |

Heterostructures composed of a 2D layered material (2DLM) and complex transition metal oxides (TMO) provide a new platform for design, realization, and examination of artificial materials that are physically intriguing and technologically useful. An overview is presented for some of the examples, where various functional properties emerge at the novel 2DLM/TMO heterostructures. Abstract The marriage between a 2D layered material (2DLM) and a complex transition metal oxide (TMO) results in a variety of physical and chemical phenomena that cannot be achieved in either material alone. Interesting recent discoveries in systems such as graphene/SrTiO3, graphene/LaAlO3/SrTiO3, graphene/ferroelectric oxide, MoS2/SrTiO3, and FeSe/SrTiO3 heterostructures include voltage scaling in field‐effect transistors, charge state coupling across an interface, quantum conductance probing of the electrochemical activity, novel memory functions based on charge traps, and greatly enhanced superconductivity. In this context, various properties and functionalities appearing in numerous different 2DLM/TMO heterostructure systems are reviewed. The results imply that the multidimensional heterostructure approach based on the disparate material systems leads to an entirely new platform for the study of condensed matter physics and materials science. The heterostructures are also highly relevant technologically as each constituent material is a promising candidate for next‐generation optoelectronic devices.

Published in: "Advanced Materials".

Realization of continuous electron doping in bulk iron selenides and identification of a new superconducting zone

2018-12-12T16:33:55+00:00December 12th, 2018|Categories: Publications|Tags: |

Author(s): R. J. Sun, Y. Quan, S. F. Jin, Q. Z. Huang, H. Wu, L. Zhao, L. Gu, Z. P. Yin, and X. L. ChenIron selenide superconductors exhibit unique characteristics distinct from iron pnictides, especially in the electron-doped region. Here, the authors report the synthesis of a new family of Lix(C3N2H10)0.37FeSe materials, which features a continuous superconducting dome harboring a Lifshitz transition within the wide range of 0.06≤x≤0.68. Under electron doping, the anion height of FeSe layers deviates linearly away from the optimized values of pnictides. This feature leads to a new superconducting zone with unique electronic structures and strong orbital-selective electronic correlation.[Phys. Rev. B 98, 214508] Published Wed Dec 12, 2018

Published in: "Physical Review B".

The stability of exfoliated FeSe nanosheets during in-air device fabrication process. (arXiv:1805.02805v1 [cond-mat.mtrl-sci])

2018-05-09T19:59:00+00:00May 9th, 2018|Categories: Publications|Tags: |

We studied the stability and superconductivity of FeSe nanosheets during an in-air device fabrication process. Methods were developed to improve the exfoliation yield and to maintain the superconductivity of FeSe. Raman spectroscopy, atomic force microscopy, optical microscopy and time-of-flight-secondary-ion-mass-spectroscopy measurements show that FeSe nanosheets decayed in air. Precipitation of Se particles and iron oxidation likely occurred during the decay process. Transport measurements revealed that the superconductivity of FeSe disappeared during a conventional electron beam lithography process. Shadow mask evaporation and transfer onto pre-defined electrodes methods were shown to be effective in maintaining the superconductivity after the in-air device fabrication process. These methods developed provide a way of making high quality FeSe nano-devices.

Published : "arXiv Mesoscale and Nanoscale Physics".

Direct imaging of electron transfer and its influence on superconducting pairing at FeSe/SrTiO3 interface

2018-03-16T20:32:30+00:00March 16th, 2018|Categories: Publications|Tags: , |

The exact mechanism responsible for the significant enhancement of the superconducting transition temperature (Tc) of monolayer iron selenide (FeSe) films on SrTiO3 (STO) over that of bulk FeSe is an open issue. We present the results of a coordinated study of electrical transport, low temperature electron energy-loss spectroscopy (EELS), and

Published in: "Science Advances".

Coexistence of multiphase superconductivity and ferromagnetism in lithiated iron selenide hydroxide $[(mathrm{L}{mathrm{i}}_{1−x}mathrm{F}{mathrm{e}}_{x})mathrm{OH}]mathrm{FeSe}$

2018-01-25T14:30:35+00:00January 25th, 2018|Categories: Publications|Tags: |

Author(s): Christian Urban, Ilya Valmianski, Ursula Pachmayr, Ali C. Basaran, Dirk Johrendt, and Ivan K. SchullerWe present experimental evidence for (a) multiphase superconductivity and (b) coexistence of magnetism and superconductivity in a single structural phase of lithiated iron selenide hydroxide [(Li1−xFex)OH]FeSe. Magnetic field modulated microwave spectroscopy data confirms superconductivity with at l…[Phys. Rev. B 97, 024516] Published Thu Jan 25, 2018

Published in: "Physical Review B".

Liquid phase mass production of air-stable black phosphorus/phospholipids nanocomposite with ultralow tunneling barrier. (arXiv:1801.06997v1 [cond-mat.mtrl-sci])

2018-01-23T20:00:54+00:00January 23rd, 2018|Categories: Publications|Tags: , , , |

Few-layer black phosphorus (FLBP), a recently discovered two-dimensional semiconductor, has attracted substantial attention in the scientific and technical communities due to its great potential in electronic and optoelectronic applications. However, reactivity of FLBP flakes with ambient species limits its direct applications. Among various methods to passivate FLBP in ambient environment, nanocomposites mixing FLBP flakes with stable matrix may be one of the most promising approaches for industry applications. Here, we report a simple one-step procedure to mass produce air-stable FLBP/phospholipids nanocomposite in liquid phase. The resultant nanocomposite is found to have ultralow tunneling barrier for charge carriers which can be described by an Efros-Shklovskii variable range hopping mechanism. Devices made from such mass-produced FLBP/phospholipids nanocomposite show highly stable electrical conductivity and opto-electrical response in ambient conditions, indicating its promising applications in both electronic and optoelectronic applications. This method could also be generalized to the mass production of nanocomposites consisting of other air-sensitive two-dimensional materials, such as FeSe, NbSe2, WTe2, etc.

Published in: "arXiv Material Science".

Compression of Wannier functions into Gaussian-type orbitals. (arXiv:1712.02996v1 [cond-mat.mtrl-sci])

2017-12-11T19:59:54+00:00December 11th, 2017|Categories: Publications|Tags: , |

We propose a greedy algorithm for the compression of Wannier functions into Gaussian-polynomials orbitals. The so-obtained compressed Wannier functions can be stored in a very compact form, and can be used to efficiently parameterize effective tight-binding Hamiltonians for multilayer 2D materials for instance. The compression method preserves the symmetries (if any) of the original Wannier function. We provide algorithmic details, and illustrate the performance of our implementation on several examples, including graphene, hexagonal boron-nitride, single-layer FeSe, and bulk silicon in the diamond cubic structure.

Published in: "arXiv Material Science".

Sign reversal of the order parameter in (Li<sub>1−<i>x</i></sub>Fe<sub><i>x</i></sub>)OHFe<sub>1−<i>y</i></sub>Zn<sub><i>y</i></sub>Se

2017-10-24T18:30:26+00:00October 24th, 2017|Categories: Publications|Tags: |

Sign reversal of the order parameter in (Li1−xFex)OHFe1−yZnySeNature Physics, Published online: 23 October 2017; doi:10.1038/nphys4299A scanning tunnelling microscopy study of an intercalated iron selenide-based superconductor reveals a sign change in its superconducting gap function, providing indirect evidence for the origin of the pairing mechanism in this system.

Published in: "Nature Physics".

Stripes developed at the strong limit of nematicity in FeSe film

2017-10-05T14:30:46+00:00October 5th, 2017|Categories: Publications|Tags: |

Nature Physics 13, 957 (2017). doi:10.1038/nphys4186 Authors: Wei Li, Yan Zhang, Peng Deng, Zhilin Xu, S.-K. Mo, Ming Yi, Hao Ding, M. Hashimoto, R. G. Moore, D.-H. Lu, Xi Chen, Z.-X. Shen & Qi-Kun Xue A single monolayer of iron selenide grown on strontium titanate shows an impressive enhancement of superconductivity compared with the bulk, as well as a novel Fermi surface topology, extreme two-dimensionality, and the possibility of phonon-enhanced electron pairing. For films thicker than one unit cell, however, the electronic structure is markedly different, with a drastically suppressed superconductivity and strong nematicity appearing. The physics driving this extraordinary dichotomy of superconducting behaviour is far from clear. Here, we use low-temperature scanning tunnelling microscopy to study multilayers of iron selenide grown by molecular beam epitaxy, and find a stripe-type charge ordering instability that develops beneath the nematic state. The charge ordering is visible and pinned in the vicinity of impurities. And as it emerges in the strong limit of nematicity, it suggests that a magnetic fluctuation with a rather small wavevector may be competing with the ordinary collinear antiferromagnetic ordering in multilayer films. The existence of stripes in iron-based superconductors, which resemble the stripe order in cuprates, not only suggests that electronic anisotropy and correlation are playing an important role, but also provides a platform for probing the complex interactions between nematicity, charge ordering, magnetism and superconductivity in high-temperature superconductors.

Published in: "Nature Physics".

Basic electronic properties of iron selenide under variation of structural parameters. (arXiv:1706.03543v2 [cond-mat.supr-con] UPDATED)

2017-09-07T19:59:01+00:00September 7th, 2017|Categories: Publications|Tags: |

Since the discovery of high-temperature superconductivity in the thin-film FeSe/SrTiO$_3$ system, iron selenide and its derivates have been intensively scrutinized. Using ab initio density functional theory calculations we review the electronic structures that could be realized in iron-selenide if the structural parameters could be tuned at liberty. We calculate the momentum-dependence of the susceptibility and investigate the symmetry of electron pairing within the random phase approximation. Both the susceptibility and the symmetry of electron pairing depend on the structural parameters in a nontrivial way. These results are consistent with the known experimental behavior of binary iron chalcogenides and, at the same time, reveal two promising new ways of tuning superconducting transition temperatures in these materials. On the one hand by expanding the iron lattice of FeSe at constant iron-selenium distance and, on the other hand, by increasing the iron-selenium distance with unchanged iron lattice.

Published in: "arXiv Material Science".

Basic electronic properties of iron selenide under variation of structural parameters

2017-09-06T16:29:43+00:00September 6th, 2017|Categories: Publications|Tags: |

Author(s): Daniel Guterding, Harald O. Jeschke, and Roser ValentíSince the discovery of high-temperature superconductivity in the thin-film FeSe/SrTiO3 system, iron selenide and its derivates have been intensively scrutinized. Using ab initio density functional theory calculations we review the electronic structures that could be realized in iron selenide if the …[Phys. Rev. B 96, 125107] Published Wed Sep 06, 2017

Published in: "Physical Review B".

High-Tc Superconducting Phases in Organic Molecular Intercalated Iron Selenides: Synthesis and Crystal Structures

2017-07-31T10:29:42+00:00July 31st, 2017|Categories: Publications|Tags: |

Chem. Commun., 2017, Accepted ManuscriptDOI: 10.1039/C7CC05242A, CommunicationShifeng Jin, Xiao Fan, Ruijin Sun, Xiaozhi Wu, Hui Wu, Qingzhen Huang, Chenlong Shi, Xuiqui Xi, Zhilin Li, Xiaolong ChenHybrid iron-based superconductors were synthesized by sonochemical insertion of organic molecules into FeSe layers. High quality of the samples firstly enables reliable phase identifications and three structure types are discovered….The content of this RSS Feed (c) The Royal Society of Chemistry

Published in: "Chemical Communications".

Some say, that 2D Research is the best website in the world.