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Jörg Schmalian - One of the best experts on this subject based on the ideXlab platform.
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Orbital loop currents in Iron-Based Superconductors
Physical Review B, 2018Co-Authors: Markus J. Klug, Jian Kang, Rafael M. Fernandes, Jörg SchmalianAbstract:We show that the stripe spin-density wave state commonly observed in the phase diagrams of the Iron-Based Superconductors necessarily triggers loop currents characterized by charge transfer between different Fe 3d orbitals. This effect is rooted on the glide-plane symmetry of these materials and on the existence of an atomic spin-orbit coupling that couples states at the $X$ and $Y$ points of the 1-Fe Brillouin zone. In the particular case in which the spins are aligned parallel to the magnetic ordering vector direction which is the spin configuration most commonly found in the Iron-Based Superconductors these loop currents involve the $d_{xy}$ orbital and either the $d_{yz}$ orbital (if the spins point along the $y$ axis) or the $d_{xz}$ orbitals (if the spins point along the $x$ axis). We show that the two main manifestations of the orbital loop currents are the emergence of magnetic moments in the pnictide/chalcogen site and an orbital-selective band splitting in the magnetically ordered state, both of which could be detected experimentally. Our results highlight the unique intertwining between orbital and spin degrees of freedom in the Iron-Based Superconductors, and reveal the emergence of an unusual correlated phase that may impact the normal state and superconducting properties of these materials.
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Nematic Resonance in the Raman Response of Iron-Based Superconductors.
Physical review letters, 2016Co-Authors: Yann Gallais, I. Paul, L. Chauviere, Jörg SchmalianAbstract:In a fully gapped superconductor the electronic Raman response has a pair-breaking peak at twice the superconducting gap Δ, if the Bogoliubov excitations are uncorrelated. Motivated by the iron based Superconductors, we study how this peak is modified if the superconducting phase hosts a nematic-structural quantum critical point. We show that, upon approaching this point by tuning, e.g., doping, the growth of nematic correlations between the quasiparticles transforms the pair-breaking peak into a nematic resonance. The mode energy is below 2Δ, and stays finite at the quantum critical point, where its spectral weight is sharply enhanced. The latter is consistent with recent experiments on electron-doped iron based Superconductors and provides direct evidence of nematic correlations in their superconducting phases.
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Pair-breaking due to orbital magnetism in Iron-Based Superconductors
Physical Review B, 2015Co-Authors: M. Hoyer, Mathias S. Scheurer, Sergey Syzranov, Jörg SchmalianAbstract:We consider superconductivity in the presence of impurities in a two-band model suited for the description of Iron-Based Superconductors. We analyze the effect of interband scattering processes on superconductivity, allowing for orbital, i.e., nonspin-magnetic but time-reversal symmetry-breaking impurities. Pair breaking in such systems is described by a nontrivial phase in an interband-scattering matrix element. We find that the transition temperature of conventional Superconductors can be suppressed due to interband scattering, whereas unconventional Superconductors may be unaffected. We also discuss the stability of density wave phases in the presence of impurities. As an example, we consider impurities associated with imaginary charge density waves that are of interest for Iron-Based Superconductors.
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what drives nematic order in iron based Superconductors
Nature Physics, 2014Co-Authors: Rafael M. Fernandes, Andrey V Chubukov, Jörg SchmalianAbstract:Nematic order in the Iron-Based Superconductors breaks the symmetry between the x and y directions in the Fe plane. Beyond this, however, there is little consensus on how nematic order arises and whether it has an effect on superconductivity. This Review discusses the current theoretical and experimental state of the field.
Hiroshi Ikuta - One of the best experts on this subject based on the ideXlab platform.
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p-wave superconductivity in Iron-Based Superconductors.
Scientific reports, 2019Co-Authors: Evgueni F. Talantsev, Kazumasa Iida, T. Ohmura, Takuya Matsumoto, W. P. Crump, N. M. Strickland, Stuart C. Wimbush, Hiroshi IkutaAbstract:The possibility of p-wave pairing in Superconductors has been proposed more than five decades ago, but has not yet been convincingly demonstrated. One difficulty is that some p-wave states are thermodynamically indistinguishable from s-wave, while others are very similar to d-wave states. Here we studied the self-field critical current of NdFeAs(O,F) thin films in order to extract absolute values of the London penetration depth, the superconducting energy gap, and the relative jump in specific heat at the superconducting transition temperature, and find that all the deduced physical parameters strongly indicate that NdFeAs(O,F) is a bulk p-wave superconductor. Further investigation revealed that single atomic layer FeSe also shows p-wave pairing. In an attempt to generalize these findings, we re-examined the whole inventory of superfluid density measurements in Iron-Based Superconductors and show quite generally that single-band weak-coupling p-wave superconductivity is exhibited in Iron-Based Superconductors.
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p-Wave Superconductivity in Iron-Based Superconductors
Scientific reports, 2019Co-Authors: Evgueni F. Talantsev, Kazumasa Iida, T. Ohmura, Takuya Matsumoto, W. P. Crump, N. M. Strickland, Stuart C. Wimbush, Hiroshi IkutaAbstract:The possibility of p-wave pairing in Superconductors has been proposed more than five decades ago, but has not yet been convincingly demonstrated. One difficulty is that some p-wave states are thermodynamically indistinguishable from s-wave, while others are very similar to d-wave states. Here we studied the self-field critical current of NdFeAs(O,F) thin films in order to extract absolute values of the London penetration depth, the superconducting energy gap, and the relative jump in specific heat at the superconducting transition temperature, and find that all the deduced physical parameters strongly indicate that NdFeAs(O,F) is a bulk p-wave superconductor. Further investigation revealed that single atomic layer FeSe also shows p-wave pairing. In an attempt to generalize these findings, we re-examined the whole inventory of superfluid density measurements in Iron-Based Superconductors show quite generally that most of the Iron-Based Superconductors are p-wave Superconductors.
Jiangping Hu - One of the best experts on this subject based on the ideXlab platform.
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Longitudinal modes of spin fluctuations in Iron-Based Superconductors
Physical Review B, 2017Co-Authors: Qiang Zhang, Jiangping HuAbstract:Iron-Based Superconductors can exhibit different magnetic ground states and are in a critical magnetic region where frustrated magnetic interactions strongly compete with each other. Here we investigate the longitudinal modes of spin fluctuations in an unified effective magnetic model for Iron-Based Superconductors. We focus on the collinear antiferromagnetic phase (CAF) and calculate the behavior of the longitudinal modes when different phase boundaries are approached. The results can help to determine the nature of the magnetic fluctuations in Iron-Based Superconductors.
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iron based Superconductors as odd parity Superconductors
Physical Review X, 2013Co-Authors: Jiangping HuAbstract:Parity is a fundamental quantum number used to classify a state of matter. Materials rarely possess ground states with odd parity. We show that the superconducting state in Iron-Based Superconductors is classified as an odd-parity s-wave spin-singlet pairing state in a single trilayer FeAs=Se, the building block of the materials. In a low-energy effective model constructed on the Fe square bipartite lattice, the superconducting order parameter in this state is a combination of an s-wave normal pairing between two sublattices and an s-wavepairing within the sublattices. The state has a fingerprint with a real-space sign inversion between the top and bottom As=Se layers. The results suggest that Iron-Based super- conductors are a new quantum state of matter, and the measurement of the odd parity can help to establish high-temperature superconducting mechanisms. DOI: 10.1103/PhysRevX.3.031004 Subject Areas: Condensed Matter Physics, Superconductivity Symmetry plays the central role in the search for beauty in physics. It controls the structure of matter and allows us to simplify a complicated problem. The gauge principle is a fundamental principle in physics. Models formulated in different gauge settings are equivalent. Symmetry and gauge principles together provide the foundations of mod- ern physics that allow us to solve complicated problems. The recently discovered Iron-Based high-temperature Superconductors (high T c )( 1-3) are layered materials with complicated electronic structures. Their complexity causes a major difficulty in understanding pairing symme- try, which arguably is the most important property and clue to determine the pairing mechanism (4,5). In a strongly correlated electron system, major physics is determined locally in real space. Important properties, such as pairing symmetry in a superconducting state, are ex- pected to be robust against small variations of Fermi surfaces in reciprocal space. Although the superconducting mechanism related to high-temperature Superconductors (high Tc) has not yet been determined, the robust d-wave pairing symmetry in cuprates (6) can be understood under this principle. Does this principle still hold for Iron-Based supercon- ductors? Namely, do all Iron-Based Superconductors pos- sess one universal pairing state? Unlike cuprates, the answer to this question is highly controversial because different theoretical approaches have provided different answers and no universal state has been identified (5). Nevertheless, as local electronic structures in all families of Iron-Based Superconductors are almost identical and phase diagrams are smooth against doping (4,5), it is hard to argue that the materials can approach many differ- ent superconducting ground states.
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Sign Change in the Odd Parity Superconducting State of Iron-Based Superconductors
arXiv: Superconductivity, 2013Co-Authors: Jiangping HuAbstract:We discuss the sign change of superconducting order parameters in both real and reciprocal spaces in the odd parity state of Iron-Based Superconductors proposed recently in\cite{huoddparity}. In the real space, the odd parity state can be viewed as a s-wave or d-wave state depending on the choice of locations. In a 2-Fe Brilliouin zone (BZ), sign change exists between two hole pockets and between two electron pockets. In a 1-Fe BZ which includes two 2-Fe BZs, the sign change is between two 2-Fe BZs, which leads to a d-wave type sign distribution on the electron pockets. However, there is no symmetry protected gapless node on the electron pockets. This sign change character consistently explains experimental results related to sign change properties measured on both iron-pnictides and iron-chalcogenides.
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Mechanism for Odd Parity Superconductivity in Iron-Based Superconductors
arXiv: Superconductivity, 2013Co-Authors: Jiangping Hu, Xianxin WuAbstract:Under the assumption that superconducting pairing is driven by local d-p hybridization, we show that the superconducting state in Iron-Based Superconductors is classified as an odd parity s-wave spin-singlet pairing state in a single trilayer FeAs/Se, the building block of the materials. In a low energy effective model with only d-orbitals in an iron square bipartite lattice, the superconducting order parameter in this state is a combination of a s-wave normal pairing between two sublattices and a s-wave $\eta$-pairing within the sublattices. Parity conservation was violated in proposed superconducting states in the past. The results demonstrate Iron-Based Superconductors being a new quantum state of matter and suggest that a measurement of odd parity can establish fundamental principles related to high temperature superconducting mechanism.
Hideo Hosono - One of the best experts on this subject based on the ideXlab platform.
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Iron-Based Superconductors: Current status of materials and pairing mechanism
Physica C: Superconductivity and its Applications, 2015Co-Authors: Hideo Hosono, Kazuhiko KurokiAbstract:Abstract Since the discovery of high Tc Iron-Based Superconductors in early 2008, more than 15,000 papers have been published as a result of intensive research. This paper describes the current status of Iron-Based Superconductors (IBSC) covering most up-to-date research progress along with the some background research, focusing on materials (bulk and thin film) and pairing mechanism.
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Iron-Based Superconductors: Materials, Properties and Mechanisms - Iron-Based Superconductors : materials, properties, and mechanisms
2012Co-Authors: Nanlin Wang, Hideo Hosono, Pengcheng DaiAbstract:Iron-Based Superconductors: Discovery and Progress in Materials Hideo Hosono Introduction Small History on Discovery and Progress in Parent Materials Crystal Structure of Parent Materials Parent Material and Superconductivity Unique Characteristics of FeSCs Single Crystal Thin Film Summary and Relevant New Superconductors Synthesis and Physical Properties of the New Potassium Iron Selenide Superconductor R. Hu, E. D. Mun, D. H. Ryan, K. Cho, H. Kim, H. Hodovanets, W. E. Straszheim, M. A. Tanatar, R. Prozorov, W. N. Rowan-Weetaluktuk, J. M. Cadogan, M.M. Altarawneh, C. H. Mielke, V. S. Zapf, S. L. Budko, and P. C. Canfield Introduction Experimental Methods Crystal Growth and Stoichiometry Physical Properties of Single Crystals of K0.80Fe1.76Se2 Summary Angle-Resolved Photoemission Spectroscopy of Iron Pnictides Takafumi Sato, Pierre Richard, Kosuke Nakayama, Takashi Takahashi, and Hong Ding Introduction Experimental Results Concluding Remarks and Summary Quantum Oscillations in Iron Pnictide Superconductors Suchitra E. Sebastian Quantum Oscillations Magnetic Field Dependence Temperature Dependence Iron Pnictide Superconductors Quantum Oscillations in Antiferromagnetic Parent Iron Pnictides Quantum Oscillations in Overdoped Paramagnetic Iron Pnictides Cuprates and Iron Pnictides: Electronic Structure Comparison Conclusion Optical Investigation on Iron-Based Superconductors Nan-LinWang and Zhi-Guo Chen Introduction Introduction About Optical Properties of Solids Optical Studies on the Parent Compounds Multi-Components vs. Extended Drude Model Analysis of Optical Conductivity Electron Correlations in the Fe-Pnictides/Chalcogenides Anisotropic Charge Dynamics Optical Properties of Iron-Based Superconductors Below Tc Antiferromagnetic Spin Fluctuations in the Fe-Based Superconductors Shiliang Li and Pengcheng Dai Introduction Antiferromagnetism in Parent Compounds Magnetic Excitations in the Superconducting State Magnetic Excitations in the Normal State Conclusion Review of NMR Studies on Iron-Based Superconductors Kenji Ishida and Yusuke Nakai Introduction NMR Basics NMR Experimental Results on Iron-Based Superconductors Summary Material Specific Model Hamiltonians and Analysis on the Pairing Mechanism Kazuhiko Kuroki Introduction Model Hamiltonian Construction Spin Fluctuations and Antiferromagnetism Superconductivity Material Dependence Concluding Remarks and Perspectives The Antiferromagnetic Phase of Iron-Based Superconductors: An Itinerant Approach Johannes Knolle and Ilya Eremin Introduction A Primer: Single-Band Hubbard Model Magnetic Order in Ferropnictides SpinWaves in Itinerant Multiorbital Systems Discussion and Conclusion Magnetism in Parent Compounds of Iron-Based Superconductors Jiangping Hu Introduction Experimental Results on the Parent Compounds of Iron-Based Superconductors Theoretical Models Electronic Nematism and the Interplay Between Lattice, Spin and Orbital Discussion
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thin film growth and device fabrication of iron based Superconductors
Journal of the Physical Society of Japan, 2012Co-Authors: Hidenori Hiramatsu, Takayoshi Katase, Toshio Kamiya, Hideo HosonoAbstract:Iron-Based Superconductors have received much attention as a new family of high-temperature Superconductors owing to their unique properties and distinct differences from cuprates and conventional Superconductors. This paper reviews progress in thin film research on Iron-Based Superconductors since their discovery for each of five material systems with an emphasis on growth, physical properties, device fabrication, and relevant bulk material properties.
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Thin Film Growth and Device Fabrication of Iron-Based Superconductors
Journal of the Physical Society of Japan, 2012Co-Authors: Hidenori Hiramatsu, Takayoshi Katase, Toshio Kamiya, Hideo HosonoAbstract:Iron-Based Superconductors have received much attention as a new family of high-temperature Superconductors owing to their unique properties and distinct differences from cuprates and conventional Superconductors. This paper reviews progress in thin film research on Iron-Based Superconductors since their discovery for each of five material systems with an emphasis on growth, physical properties, device fabrication, and relevant bulk material properties. (*) E-mail address: h-hirama@lucid.msl.titech.ac.jp
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Iron based Superconductors processing and properties
International Materials Reviews, 2012Co-Authors: Satoru Fujitsu, Satoru Matsuishi, Hideo HosonoAbstract:The discovery of iron based Superconductors in early 2008 stimulated the interest of researchers around the globe, including physicists, chemists and materials scientists leading to publication of more than 4000 papers on this superconductor since then. Since the major player in the superconductor is iron, which had long been believed to be the worst element suited for the superconductivity, this discovery gave tremendous impact on the superconductivity research. Furthermore, this material has favourable characteristics for practical applications such as a relatively high critical temperature, high upper critical field and high critical current density with low anisotropy. In the last 3 years, many derived superconducting materials have been discovered and several theoretical models for the mechanism of superconductivity have been proposed. In this review, the research topics on iron based Superconductors are summarised from the viewpoint of materials science.
Evgueni F. Talantsev - One of the best experts on this subject based on the ideXlab platform.
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p-wave superconductivity in Iron-Based Superconductors.
Scientific reports, 2019Co-Authors: Evgueni F. Talantsev, Kazumasa Iida, T. Ohmura, Takuya Matsumoto, W. P. Crump, N. M. Strickland, Stuart C. Wimbush, Hiroshi IkutaAbstract:The possibility of p-wave pairing in Superconductors has been proposed more than five decades ago, but has not yet been convincingly demonstrated. One difficulty is that some p-wave states are thermodynamically indistinguishable from s-wave, while others are very similar to d-wave states. Here we studied the self-field critical current of NdFeAs(O,F) thin films in order to extract absolute values of the London penetration depth, the superconducting energy gap, and the relative jump in specific heat at the superconducting transition temperature, and find that all the deduced physical parameters strongly indicate that NdFeAs(O,F) is a bulk p-wave superconductor. Further investigation revealed that single atomic layer FeSe also shows p-wave pairing. In an attempt to generalize these findings, we re-examined the whole inventory of superfluid density measurements in Iron-Based Superconductors and show quite generally that single-band weak-coupling p-wave superconductivity is exhibited in Iron-Based Superconductors.
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p-Wave Superconductivity in Iron-Based Superconductors
Scientific reports, 2019Co-Authors: Evgueni F. Talantsev, Kazumasa Iida, T. Ohmura, Takuya Matsumoto, W. P. Crump, N. M. Strickland, Stuart C. Wimbush, Hiroshi IkutaAbstract:The possibility of p-wave pairing in Superconductors has been proposed more than five decades ago, but has not yet been convincingly demonstrated. One difficulty is that some p-wave states are thermodynamically indistinguishable from s-wave, while others are very similar to d-wave states. Here we studied the self-field critical current of NdFeAs(O,F) thin films in order to extract absolute values of the London penetration depth, the superconducting energy gap, and the relative jump in specific heat at the superconducting transition temperature, and find that all the deduced physical parameters strongly indicate that NdFeAs(O,F) is a bulk p-wave superconductor. Further investigation revealed that single atomic layer FeSe also shows p-wave pairing. In an attempt to generalize these findings, we re-examined the whole inventory of superfluid density measurements in Iron-Based Superconductors show quite generally that most of the Iron-Based Superconductors are p-wave Superconductors.
