1
|
Obata Y, Sato M, Kondo Y, Yamaguchi Y, Karateev IA, Pavlov I, Vasiliev AL, Haindl S. Chemical Composition Control at the Substrate Interface as the Key for FeSe Thin-Film Growth. ACS APPLIED MATERIALS & INTERFACES 2021; 13:53162-53170. [PMID: 34698487 DOI: 10.1021/acsami.1c14451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The strong fascination exerted by the binary compound of FeSe demands reliable engineering protocols and more effective approaches toward inducing superconductivity in FeSe thin films. Our study addresses the peculiarities in pulsed laser deposition that determine FeSe thin-film growth and focuses on the film/substrate interface, which has only been considered hypothetically in the past literature. The FeSe/MgO interface has been assumed (1) to be clean and (2) to obey lattice-matching epitaxy. Our studies reveal that both assumptions are misleading and demonstrate the tendency for domain-matching epitaxial growth, which accompanies the problem of chemical heterogeneity. We propose that homogenization of the film/substrate interface by an Fe buffer can improve the control of stoichiometry and nanostrain in a way that favors superconductivity even in ultrathin FeSe films. We will also show that on a chemically homogenized FeSe/Fe interface, the control of film texture with preparation conditions is still possible.
Collapse
Affiliation(s)
- Yukiko Obata
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Michiko Sato
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Yuji Kondo
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Yuta Yamaguchi
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Igor A Karateev
- National Research Centre ″Kurchatov Institute,″ pl. Akademika Kurchatova 1, Moscow 123182, Russian Federation
| | - Ivan Pavlov
- Shubnikov Institute of Crystallography of FSRC "Crystallography and Photonics" Russian Academy of Sciences, Leninsky pr. 59, Moscow 119333, Russian Federation
| | - Alexander L Vasiliev
- National Research Centre ″Kurchatov Institute,″ pl. Akademika Kurchatova 1, Moscow 123182, Russian Federation
- Shubnikov Institute of Crystallography of FSRC "Crystallography and Photonics" Russian Academy of Sciences, Leninsky pr. 59, Moscow 119333, Russian Federation
- Moscow Institute of Physics and Technology, National Research University, Dolgoprudny, Moscow region 141701, Russian Federation
| | - Silvia Haindl
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| |
Collapse
|
2
|
Obata Y, Karateev IA, Pavlov I, Vasiliev AL, Haindl S. Challenges for Pulsed Laser Deposition of FeSe Thin Films. MICROMACHINES 2021; 12:1224. [PMID: 34683275 PMCID: PMC8540977 DOI: 10.3390/mi12101224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/28/2021] [Accepted: 10/05/2021] [Indexed: 11/16/2022]
Abstract
Anti-PbO-type FeSe shows an advantageous dependence of its superconducting properties with mechanical strain, which could be utilized as future sensor functionality. Although superconducting FeSe thin films can be grown by various methods, ultrathin films needed in potential sensor applications were only achieved on a few occasions. In pulsed laser deposition, the main challenges can be attributed to such factors as controlling film stoichiometry (i.e., volatile elements during the growth), nucleation, and bonding to the substrate (i.e., film/substrate interface control) and preventing the deterioration of superconducting properties (i.e., by surface oxidization). In the present study, we address various technical issues in thin film growth of FeSe by pulsed laser deposition, which pose constraints in engineering and reduce the application potential for FeSe thin films in sensor devices. The results indicate the need for sophisticated engineering protocols that include interface control and surface protection from chemical deterioration. This work provides important actual limitations for pulsed laser deposition (PLD) of FeSe thin films with the thicknesses below 30 nm.
Collapse
Affiliation(s)
- Yukiko Obata
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Igor A. Karateev
- National Research Centre “Kurchatov Institute”, pl. Akademika Kurchatova 1, 123182 Moscow, Russia;
| | - Ivan Pavlov
- Shubnikov Institute of Crystallography of FSRC “Crystallography and Photonics” Russian Academy of Sciences, Leninsky pr. 59, 119333 Moscow, Russia;
| | - Alexander L. Vasiliev
- National Research Centre “Kurchatov Institute”, pl. Akademika Kurchatova 1, 123182 Moscow, Russia;
- Shubnikov Institute of Crystallography of FSRC “Crystallography and Photonics” Russian Academy of Sciences, Leninsky pr. 59, 119333 Moscow, Russia;
- Moscow Institute of Physics and Technology, National Research University, Dolgoprudny, 141701 Moscow, Russia
| | - Silvia Haindl
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| |
Collapse
|
3
|
Parvarinezhad S, Salehi M, Kademinia S, Kubicki M. The structural study, Hirshfeld surface analysis, and DFT calculations of ferrocenyl-hydrazine Schiff base: A novel precursor for the selective preparation of Fe2O3 nanoparticles. J Mol Struct 2019. [DOI: 10.1016/j.molstruc.2019.06.109] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
|
4
|
Abstract
The exact superconducting phase of K2-x Fe4+y Se5 has so far not been conclusively decided since its discovery due to its intrinsic multiphase in early material. In an attempt to resolve this mystery, we have carried out systematic structural studies on a set of well-controlled samples with exact chemical stoichiometry K2-x Fe4+x Se5 (x = 0-0.3) that are heat-treated at different temperatures. Using high-resolution synchrotron radiation X-ray diffraction, our investigations have determined the superconducting transition by focusing on the detailed temperature evolution of the crystalline phases. Our results show that superconductivity appears only in those samples that have been treated at high-enough temperature and then quenched to room temperature. The volume fraction of superconducting transition strongly depends on the annealing temperature used. The most striking result is the observation of a clear contrast in crystalline phase between the nonsuperconducting parent compound K2Fe4Se5 and the superconducting K2-x Fe4+y Se5 samples. The X-ray diffraction patterned can be well indexed to the phase with I4/m symmetry in all temperatures investigated. However, we need two phases with similar I4/m symmetry but different parameters to best fit the data at a temperature below the Fe vacancy order temperature. The results strongly suggest that superconductivity in K2-x Fe4+y Se5 critically depends on the occupation of Fe atoms on the originally empty 4d site.
Collapse
|
5
|
Tunable critical temperature for superconductivity in FeSe thin films by pulsed laser deposition. Sci Rep 2018; 8:4039. [PMID: 29511227 PMCID: PMC5840431 DOI: 10.1038/s41598-018-22291-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 02/19/2018] [Indexed: 12/01/2022] Open
Abstract
Stabilized FeSe thin films in ambient pressure with tunable superconducting critical temperature would be a promising candidate for superconducting electronic devices. By carefully controlling the depositions on twelve kinds of substrates using a pulsed laser deposition technique single crystalline FeSe thin films were fabricated. The high quality of the thin films was confirmed by X-ray diffraction with a full width at half maximum of 0.515° in the rocking curve and clear four-fold symmetry in φ-scan. The films have a maximum Tc ~ 15 K on the CaF2 substrate and were stable in ambient conditions air for more than half a year. Slightly tuning the stoichiometry of the FeSe targets, the superconducting critical temperature becomes adjustable below 15 K with quite narrow transition width less than 2 K. These FeSe thin films deposited on different substrates are optimized respectively. The Tc of these optimized films show a relation with the out-of-plane (c-axis) lattice parameter of the FeSe films.
Collapse
|
6
|
Qiu W, Ma Z, Patel D, Sang L, Cai C, Shahriar Al Hossain M, Cheng Z, Wang X, Dou SX. The Interface Structure of FeSe Thin Film on CaF 2 Substrate and its Influence on the Superconducting Performance. ACS APPLIED MATERIALS & INTERFACES 2017; 9:37446-37453. [PMID: 29019397 DOI: 10.1021/acsami.7b11853] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The investigations into the interfaces in iron selenide (FeSe) thin films on various substrates have manifested the great potential of showing high-temperature-superconductivity in this unique system. In present work, we obtain FeSe thin films with a series of thicknesses on calcium fluoride (CaF2) (100) substrates and glean the detailed information from the FeSe/CaF2 interface by using scanning transmission electron microscopy (STEM). Intriguingly, we have found the universal existence of a calcium selenide (CaSe) interlayer with a thickness of approximate 3 nm between FeSe and CaF2 in all the samples, which is irrelevant to the thickness of FeSe layers. A slight Se deficiency occurs in the FeSe layer due to the formation of CaSe interlayer. This Se deficiency is generally negligible except for the case of the ultrathin FeSe film (8 nm in thickness), in which the stoichiometric deviation from FeSe is big enough to suppress the superconductivity. Meanwhile, in the overly thick FeSe layer (160 nm in thickness), vast precipitates are found and recognized as Fe-rich phases, which brings about degradation in superconductivity. Consequently, the thickness dependence of superconducting transition temperature (Tc) of FeSe thin films is investigated and one of our atmosphere-stable FeSe thin film (127 nm) possesses the highest Tconset/Tczero as 15.1 K/13.4 K on record to date in the class of FeSe thin film with practical thickness. Our results provide a new perspective for exploring the mechanism of superconductivity in FeSe thin film via high-resolution STEM. Moreover, approaches that might improve the quality of FeSe/CaF2 interfaces are also proposed for further enhancing the superconducting performance in this system.
Collapse
Affiliation(s)
- Wenbin Qiu
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong , Squires Way, North Wollongong, New South Wales 2500, Australia
- Shanghai Key Laboratory of High Temperature Superconductors, Physics Department, Shanghai University , Shanghai 200444, People's Republic of China
| | - Zongqing Ma
- Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science & Engineering, Tianjin University , Tianjin 300072, People's Republic of China
| | - Dipak Patel
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong , Squires Way, North Wollongong, New South Wales 2500, Australia
| | - Lina Sang
- Shanghai Key Laboratory of High Temperature Superconductors, Physics Department, Shanghai University , Shanghai 200444, People's Republic of China
| | - Chuanbing Cai
- Shanghai Key Laboratory of High Temperature Superconductors, Physics Department, Shanghai University , Shanghai 200444, People's Republic of China
| | - Mohammed Shahriar Al Hossain
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong , Squires Way, North Wollongong, New South Wales 2500, Australia
| | - Zhenxiang Cheng
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong , Squires Way, North Wollongong, New South Wales 2500, Australia
| | - Xiaolin Wang
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong , Squires Way, North Wollongong, New South Wales 2500, Australia
| | - Shi Xue Dou
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong , Squires Way, North Wollongong, New South Wales 2500, Australia
| |
Collapse
|
7
|
Electric field-induced superconducting transition of insulating FeSe thin film at 35 K. Proc Natl Acad Sci U S A 2016; 113:3986-90. [PMID: 27035956 DOI: 10.1073/pnas.1520810113] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It is thought that strong electron correlation in an insulating parent phase would enhance a critical temperature (Tc) of superconductivity in a doped phase via enhancement of the binding energy of a Cooper pair as known in high-Tc cuprates. To induce a superconductor transition in an insulating phase, injection of a high density of carriers is needed (e.g., by impurity doping). An electric double-layer transistor (EDLT) with an ionic liquid gate insulator enables such a field-induced transition to be investigated and is expected to result in a high Tc because it is free from deterioration in structure and carrier transport that are in general caused by conventional carrier doping (e.g., chemical substitution). Here, for insulating epitaxial thin films (∼10 nm thick) of FeSe, we report a high Tc of 35 K, which is 4× higher than that of bulk FeSe, using an EDLT under application of a gate bias of +5.5 V. Hall effect measurements under the gate bias suggest that highly accumulated electron carrier in the channel, whose area density is estimated to be 1.4 × 10(15) cm(-2) (the average volume density of 1.7 × 10(21) cm(-3)), is the origin of the high-Tc superconductivity. This result demonstrates that EDLTs are useful tools to explore the ultimate Tc for insulating parent materials.
Collapse
|
8
|
Huang J, Chen L, Jian J, Tyler K, Li L, Wang H, Wang H. Magnetic (CoFe2O4)0.1(CeO2)0.9 nanocomposite as effective pinning centers in FeSe0.1Te0.9 thin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:025702. [PMID: 26654936 DOI: 10.1088/0953-8984/28/2/025702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Magnetic epitaxial (CoFe2O4)0.1(CeO2)0.9 nanocomposite layers were incorporated into superconducting FeSe0.1Te0.9 thin films as either a cap layer or a buffer layer. Both capped and buffered samples show an enhancement of the superconducting property compared to the reference sample without the incorporated layer, while the capped one shows the best pinning properties of all the samples. Specifically for the capped sample, the critical temperature Tc is ~12.5 K, while the self-field critical current density J(c)(sf )increases to as high as 1.20 MA cm(-2) at 4 K. Its J(c)(in-field) value shows a slower decrease with increasing applied magnetic field, with the lowest power-law exponent α values (derived following Jc[formula: see text](μ0H)(-α) by the log(Jc) − log(μ0H) plot) of 0.20, 0.23 and 0.33 at 2 K, 4 K and 8 K, respectively. This nanocomposite capped sample also exhibits a high upper critical field Hc2(0) of 166 T, which indicates its potential in high field applications. This pinning method provides an effective way of enhancing the superconducting property of iron chalcogenide thin film.
Collapse
Affiliation(s)
- Jijie Huang
- Department of Material Science and Engineering, Texas A&M University, College Station, TX 77843-3003, USA
| | | | | | | | | | | | | |
Collapse
|
9
|
Shchichko IO, Presnyakov MY, Stepantsov EA, Kazakov SM, Antipov EV, Makarova IP, Vasil’ev AL. Electron microscopy of iron chalcogenide FeTe(Se) films. CRYSTALLOGR REP+ 2015. [DOI: 10.1134/s1063774515030165] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
10
|
Schneider R, Zaitsev AG, Fuchs D, von Löhneysen H. Excess conductivity and Berezinskii-Kosterlitz-Thouless transition in superconducting FeSe thin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:455701. [PMID: 25319094 DOI: 10.1088/0953-8984/26/45/455701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Temperature-dependent electronic transport in the vicinity of the superconducting transition is reported for quasi-two-dimensional textured FeSe thin films. The conspicuous rounding of the resistive transitions and large transition widths are indications of excess conductivity due to thermal Cooper-pair fluctuations, which can be well-described by the two-dimensional Aslamazov-Larkin theory. The Halperin-Nelson form of the sheet resistance between the phase-ordering temperature TBKT and the mean-field temperature TMF, and the power-law behaviour of the voltage-current characteristics, with a distinctive jump of the exponent at TBKT, are indicative of a Berezinskii-Kosterlitz-Thouless transition. The complementary results suggest a two-dimensional character of superconductivity in the FeSe films and allow a quantitative estimate of the Ginzburg number Gi.
Collapse
Affiliation(s)
- R Schneider
- Institut für Festkörperphysik, Karlsruher Institut für Technologie, D-76021 Karlsruhe, Germany
| | | | | | | |
Collapse
|
11
|
Haindl S, Kidszun M, Oswald S, Hess C, Buchner B, Kolling S, Wilde L, Thersleff T, Yurchenko VV, Jourdan M, Hiramatsu H, Hosono H. Thin film growth of Fe-based superconductors: from fundamental properties to functional devices. A comparative review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2014; 77:046502. [PMID: 24695004 DOI: 10.1088/0034-4885/77/4/046502] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Fe-based superconductors bridge a gap between MgB2 and the cuprate high temperature superconductors as they exhibit multiband character and transition temperatures up to around 55 K. Investigating Fe-based superconductors thus promises answers to fundamental questions concerning the Cooper pairing mechanism, competition between magnetic and superconducting phases, and a wide variety of electronic correlation effects. The question addressed in this review is, however, is this new class of superconductors also a promising candidate for technical applications? Superconducting film-based technologies range from high-current and high-field applications for energy production and storage to sensor development for communication and security issues and have to meet relevant needs of today’s society and that of the future. In this review we will highlight and discuss selected key issues for Fe-based superconducting thin film applications. We initially focus our discussion on the understanding of physical properties and actual problems in film fabrication based on a comparison of different observations made in the last few years. Subsequently we address the potential for technological applications according to the current situation.
Collapse
|
12
|
Abstract
Several superconducting transition temperatures in the range of 30-46 K were reported in the recently discovered intercalated FeSe system (A1-xFe2-ySe2, A = K, Rb, Cs, Tl). Although the superconducting phases were not yet conclusively decided, more than one magnetic phase with particular orders of iron vacancy and/or potassium vacancy were identified, and some were argued to be the parent phase. Here we show the discovery of the presence and ordering of iron vacancy in nonintercalated FeSe (PbO-type tetragonal β-Fe1-xSe). Three types of iron-vacancy order were found through analytical electron microscopy, and one was identified to be nonsuperconducting and magnetic at low temperature. This discovery suggests that the rich-phases found in A1-xFe2-ySe2 are not exclusive in Fe-Se and related superconductors. In addition, the magnetic β-Fe1-xSe phases with particular iron-vacancy orders are more likely to be the parent phase of the FeSe superconducting system instead of the previously assigned β-Fe1+δTe.
Collapse
|
13
|
Wu MK, Wang MJ, Yeh KW. Recent advances in β-FeSe 1-x and related superconductors. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2013; 14:014402. [PMID: 27877558 PMCID: PMC5090576 DOI: 10.1088/1468-6996/14/1/014402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 11/20/2012] [Indexed: 06/06/2023]
Abstract
It has been more than four years since the discovery of β-FeSe1-x superconductors. Through the efforts of many outstanding research groups, unprecedented advances in the field have been achieved. High-quality single crystals of β-FeSe1-x and related compounds have been prepared by various techniques, allowing us to explore in detail the physical properties of this class of materials. Detailed characterizations of the structure and properties of these crystals have helped us to understand the origin of superconductivity in β-FeSe1-x . The occurrence of superconductivity is associated with the low-temperature structure distortion, which is accompanied by several anomalies. Recent measurements on quasiparticle and acoustic phonon dynamics with respect to the orbital modification in β-FeSe1-x suggest the opening of an energy gap below 130-140 K, accompanied by a coincident transfer of optical spectral weight in the visible range and alterations in transport properties. These observations provide convincing evidence that the modification of the electronic structure occurs prior to the lattice distortion. They further suggest that the high-temperature gap and the lattice symmetry breaking are driven by short-range orbital and/or charge orders.
Collapse
Affiliation(s)
- Maw-Kuen Wu
- Department of Physics, National Dong-Hwa University, Hualien, Taiwan
- Institute of Physics, Academia Sinica, Taipei, Taiwan
| | - Ming-Jye Wang
- Institute of Physics, Academia Sinica, Taipei, Taiwan
- Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan
| | - Kuo-Wei Yeh
- Institute of Physics, Academia Sinica, Taipei, Taiwan
| |
Collapse
|
14
|
Simonelli L, Saini NL, Mizuguchi Y, Takano Y, Mizokawa T, Baldi G, Monaco G. Electronic properties of FeSe(1-x)Te(x) probed by x-ray emission and absorption spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:415501. [PMID: 23006467 DOI: 10.1088/0953-8984/24/41/415501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The electronic structure of FeSe(1-x)Te(x) chalcogenide superconductors has been studied by x-ray emission (XES) and x-ray absorption (XAS) as a function of Te substitution. The Fe Kβ XES spectra reveal a relatively low spin state for Fe in FeSe(1-x)Te(x) superconductors, persisting in the whole range of Te substitution. The Fe K-edge high-resolution XAS shows systematic spectral changes due to the evolving hybridization between the Fe 3d (4p) and chalcogen p (d) orbitals. The resonant inelastic x-ray scattering (RIXS) spectra hardly show any feature except the one due to charge transfer from occupied to unoccupied bands, that changes substantially from FeSe to FeTe. The results provide important information on the electronic states and their evolution in the FeSe(1-x)Te(x) chalcogenides.
Collapse
Affiliation(s)
- L Simonelli
- European Synchrotron Radiation Facility, Grenoble, France
| | | | | | | | | | | | | |
Collapse
|
15
|
Mele P. Superconducting properties of iron chalcogenide thin films. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2012; 13:054301. [PMID: 27877514 PMCID: PMC5099615 DOI: 10.1088/1468-6996/13/5/054301] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 11/20/2012] [Accepted: 10/03/2012] [Indexed: 06/03/2023]
Abstract
Iron chalcogenides, binary FeSe, FeTe and ternary FeTe x Se1-x , FeTe x S1-x and FeTe:O x , are the simplest compounds amongst the recently discovered iron-based superconductors. Thin films of iron chalcogenides present many attractive features that are covered in this review, such as: (i) easy fabrication and epitaxial growth on common single-crystal substrates; (ii) strong enhancement of superconducting transition temperature with respect to the bulk parent compounds (in FeTe0.5Se0.5, zero-resistance transition temperature Tc0bulk = 13.5 K, but Tc0film = 19 K on LaAlO3 substrate); (iii) high critical current density (Jc ∼ 0.5 ×106 A cm2 at 4.2 K and 0 T for FeTe0.5Se0.5 film deposited on CaF2, and similar values on flexible metallic substrates (Hastelloy tapes buffered by ion-beam assisted deposition) with a weak dependence on magnetic field; (iv) high upper critical field (∼50 T for FeTe0.5Se0.5, Bc2(0), with a low anisotropy, γ ∼ 2). These highlights explain why thin films of iron chalcogenides have been widely studied in recent years and are considered as promising materials for applications requiring high magnetic fields (20-50 T) and low temperatures (2-10 K).
Collapse
|
16
|
Singh DJ. Superconductivity and magnetism in 11-structure iron chalcogenides in relation to the iron pnictides. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2012; 13:054304. [PMID: 27877517 PMCID: PMC5099618 DOI: 10.1088/1468-6996/13/5/054304] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 10/29/2012] [Indexed: 06/03/2023]
Abstract
This is a review of the magnetism and superconductivity in '11'-type Fe chalcogenides, as compared to the Fe-pnictide materials. The chalcogenides show many differences from the pnictides, as might be anticipated from their very varied chemistries. These differences include stronger renormalizations that might imply stronger correlation effects as well as different magnetic ordering patterns. Nevertheless the superconducting state and mechanism for superconductivity are apparently similar for the two classes of materials. Unanswered questions and challenges to theory are emphasized.
Collapse
Affiliation(s)
- David Joseph Singh
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056, USA
| |
Collapse
|
17
|
Wen YC, Wang KJ, Chang HH, Luo JY, Shen CC, Liu HL, Sun CK, Wang MJ, Wu MK. Gap opening and orbital modification of superconducting FeSe above the structural distortion. PHYSICAL REVIEW LETTERS 2012; 108:267002. [PMID: 23005008 DOI: 10.1103/physrevlett.108.267002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 04/18/2012] [Indexed: 06/01/2023]
Abstract
We utilize steady-state and transient optical spectroscopies to examine the responses of nonthermal quasiparticles with respect to orbital modifications in normal-state iron-chalcogenide superconductors. The dynamics shows the emergence of gaplike quasiparticles (associated with a ~36 meV energy gap) with a coincident transfer of the optical spectral weight in the visible range, at temperatures above the structural distortion. Our observations suggest that opening of the high-temperature gap and the lattice symmetry breaking are possibly driven by short-range orbital and/or charge orders, implicating a close correlation between electronic nematicity and precursor order in iron-based superconductors.
Collapse
Affiliation(s)
- Y-C Wen
- Institute of Physics, Academia Sinica, Taipei 115, Taiwan
| | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Iadecola A, Joseph B, Puri A, Simonelli L, Mizuguchi Y, Testemale D, Proux O, Hazemann JL, Takano Y, Saini NL. Random alloy-like local structure of Fe(Se, S)(1-x)Te(x) superconductors revealed by extended x-ray absorption fine structure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:425701. [PMID: 21983016 DOI: 10.1088/0953-8984/23/42/425701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The local structure of Fe(Se, S)(1-x)Te(x) ternary (11-type) chalcogenides has been studied by temperature dependent Fe K-edge extended x-ray absorption fine structure measurements. We find that the Fe-Se and Fe-Te distances in ternary FeSe(1-x)Te(x) are closer to the respective distances in the binary systems, revealing significant divergence of the local structure from the average one. The mean square relative displacements show a systematic change with Te content, consistent with bond relaxation in the inhomogeneous ternary phases. Also, the Fe-Te and Fe-S distances in the FeS(0.2)Te(0.8) ternary system are found to be different in the crystallographically homogeneous structure. The observed features are characteristic of ternary random alloys, suggesting that a proper consideration should be given to the atomic distribution for describing the complex electronic structure of these multi-band Fe-based chalcogenides.
Collapse
Affiliation(s)
- A Iadecola
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Chen L, Yang X, Fu X, Wang C, Liang C, Wu M. Facile Solvothermal Synthesis of Uniform Iron Selenide Nanoplates. Eur J Inorg Chem 2011. [DOI: 10.1002/ejic.201001284] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
20
|
Kumar RS, Zhang Y, Sinogeikin S, Xiao Y, Kumar S, Chow P, Cornelius AL, Chen C. Crystal and Electronic Structure of FeSe at High Pressure and Low Temperature. J Phys Chem B 2010; 114:12597-606. [DOI: 10.1021/jp1060446] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ravhi S. Kumar
- Department of Physics and Astronomy and HiPSEC, University of Nevada, Las Vegas, Nevada 89154, and HPCAT, Carnegie Institution of Washington, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - Yi Zhang
- Department of Physics and Astronomy and HiPSEC, University of Nevada, Las Vegas, Nevada 89154, and HPCAT, Carnegie Institution of Washington, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - Stanislav Sinogeikin
- Department of Physics and Astronomy and HiPSEC, University of Nevada, Las Vegas, Nevada 89154, and HPCAT, Carnegie Institution of Washington, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - Yuming Xiao
- Department of Physics and Astronomy and HiPSEC, University of Nevada, Las Vegas, Nevada 89154, and HPCAT, Carnegie Institution of Washington, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - Sathish Kumar
- Department of Physics and Astronomy and HiPSEC, University of Nevada, Las Vegas, Nevada 89154, and HPCAT, Carnegie Institution of Washington, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - Paul Chow
- Department of Physics and Astronomy and HiPSEC, University of Nevada, Las Vegas, Nevada 89154, and HPCAT, Carnegie Institution of Washington, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - Andrew L. Cornelius
- Department of Physics and Astronomy and HiPSEC, University of Nevada, Las Vegas, Nevada 89154, and HPCAT, Carnegie Institution of Washington, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - Changfeng Chen
- Department of Physics and Astronomy and HiPSEC, University of Nevada, Las Vegas, Nevada 89154, and HPCAT, Carnegie Institution of Washington, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| |
Collapse
|
21
|
Huang SX, Chien CL, Thampy V, Broholm C. Control of tetrahedral coordination and superconductivity in FeSe0.5Te0.5 thin films. PHYSICAL REVIEW LETTERS 2010; 104:217002. [PMID: 20867128 DOI: 10.1103/physrevlett.104.217002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Indexed: 05/29/2023]
Abstract
We demonstrate a close relationship between superconductivity and the dimensions of the Fe-Se(Te) tetrahedron in FeSe0.5Te0.5. This is done by exploiting thin film epitaxy, which provides controlled biaxial stress, both compressive and tensile, to distort the tetrahedron. The Se/Te height within the tetrahedron is found to be of crucial importance to superconductivity, in agreement with the scenario that (π, π) spin fluctuations promote superconductivity in Fe superconductors.
Collapse
Affiliation(s)
- S X Huang
- Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | | | | | | |
Collapse
|
22
|
Wilson JA. A perspective on the Fe-based superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:203201. [PMID: 21393700 DOI: 10.1088/0953-8984/22/20/203201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
FeSe is employed as reference material to elucidate the observed high T(c) superconducting behaviour of the related layered iron pnictides. The structural and ensuing semimetallic band structural forms are here rather unusual, with the resulting ground state details extremely sensitive to the precise shape of the Fe-X coordination unit. The superconductivity is presented as coming from a combination of resonant valence bond and excitonic insulator physics, and incorporating boson-fermion degeneracy. Although sourced in a very different fashion, the latter leads to some similarities with the high temperature superconducting (HTSC) cuprates. The excitonic insulator behaviour sees spin density wave, charge density wave/periodic structural distortion, and superconductive instabilities all vie for ground state status. The conflict leads to a very sensitive and complex set of properties, frequently mirroring HTSC cuprate behaviour. The delicate balance between ground states is made particularly difficult to unravel by the micro-inhomogeneity of structural form which it can engender. It is pointed out that several other notable superconductors, layered in form, semimetallic with indirect overlap and possessing homopolar bonding, would look to fall into the same general category, β-ZrNCl and MgB(2) and the high pressure forms of several elements, like sulfur, phosphorus, lithium and calcium, being cases in point.
Collapse
Affiliation(s)
- John A Wilson
- H H Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, UK.
| |
Collapse
|
23
|
Han Y, Li WY, Cao LX, Wang XY, Xu B, Zhao BR, Guo YQ, Yang JL. Superconductivity in iron telluride thin films under tensile stress. PHYSICAL REVIEW LETTERS 2010; 104:017003. [PMID: 20366386 DOI: 10.1103/physrevlett.104.017003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Indexed: 05/25/2023]
Abstract
By realizing in thin films a tensile stress state, superconductivity of 13 K was introduced into FeTe, a nonsuperconducting parent compound of the iron pnictides and chalcogenides, with a transition temperature higher than that of its superconducting isostructural counterpart FeSe. For these tensile stressed films, superconductivity is accompanied by a softening of the first-order magnetic and structural phase transition, and also, the in-plane extension and out-of-plane contraction are universal in all FeTe films independent of the sign of the lattice mismatch, either positive or negative. Moreover, the correlations were found to exist between the transition temperatures and the tetrahedra bond angles in these thin films.
Collapse
Affiliation(s)
- Y Han
- National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | | | | | | | | | | | | | | |
Collapse
|
24
|
Chen L, Zhan H, Yang X, Sun Z, Zhang J, Xu D, Liang C, Wu M, Fang J. Composition and size tailored synthesis of iron selenide nanoflakes. CrystEngComm 2010. [DOI: 10.1039/c005097k] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|