122 iron arsenide

December 2021 thumb|Crystal structure of 122-type AEFe2Pn2 superconductors, AE = alkaline earth metal (Ca, Sr, etc.), Pn = pnictide (As, P, etc.) 10.1088/1468-6996/16/3/033503 27877784 Exploration of new superconductors and functional materials, and fabrication of superconducting tapes and wires of iron pnictides Science and Technology of Advanced Materials 16 3 033503 2015 Hosono H. Tanabe K. Takayama-Muromachi E. Kageyama H. Yamanaka S. Kumakura H. Nohara M. Hiramatsu H. Fujitsu S. 5099821 2015STAdM..16c3503H 1505.02240 The 122 iron arsenide unconventional superconductors are part of a new class of iron-based superconductors. They form in the tetragonal I4/mmm, ThCr2Si2 type, crystal structure. The shorthand name "122" comes from their stoichiometry; the 122s have the chemical formula AEFe2Pn2, where AE stands for alkaline earth metal (Ca, Ba Sr or Eu) and Pn is pnictide (As, P, etc.). 10.1103/PhysRevB.78.184517 0807.3032 2008PhRvB..78r4517K Pressure-induced volume-collapsed tetragonal phase of CaFe2As2 as seen via neutron scattering Physical Review B 78 18 184517 2008 Kreyssig A. Green M. A. Lee Y. Samolyuk G. D. Zajdel P. Lynn J. W. Bud'ko S. L. Torikachvili M. S. Ni N. Nandi S. Leão J. B. Poulton S. J. Argyriou D. N. Harmon B. N. McQueeney R. J. Canfield P. C. Goldman A. I. 118703521 10.1088/0953-8984/20/45/452201 Structural and magnetic phase transitions in the ternary iron arsenides SrFe2As2 and EuFe2As2 Journal of Physics: Condensed Matter 20 45 452201 2008 Tegel M. Rotter M. Weiß V. Schappacher F. M. Pöttgen R. Johrendt D. 2008JPCM...20S2201T 0806.4782 15023921 These materials become superconducting under pressure and also upon doping. 10.1143/APEX.1.081702 Superconductivity at 26 K in (Ca1−xNax)Fe2As2 Applied Physics Express 1 081702 2008 Shirage P. M. Miyazawa K. Kito H. Eisaki H. Iyo A. 8 2008APExp...1h1702M 94498268 10.1088/0953-8984/20/32/322204 Pressure-induced superconductivity in CaFe2As2 Journal of Physics: Condensed Matter 20 32 322204 2008 Park T. Park E. Lee H. Klimczuk T. Bauer E. D. Ronning F. Thompson J. D. 2008JPCM...20F2204P 0807.0800 94568851 10.1088/0953-8984/21/1/012208 0807.1896 2009JPCM...21a2208A Superconductivity up to 29 K in SrFe2As2 and BaFe2As2 at high pressures Journal of Physics: Condensed Matter 21 012208 2009 Alireza P. L. Ko Y. T. C. Gillett J. Petrone C. M. Cole J. M. Lonzarich G. G. Sebastian S. E. 1 21817209 206027136 10.1088/0953-8984/21/26/265701 0812.1131 2009JPCM...21z5701A Superconductivity and magnetism in K-doped EuFe2As2 Journal of Physics: Condensed Matter 21 26 265701 2009 Anupam Paulose P. L. Jeevan H. S. Geibel C. Hossain Z. 21828476 18250230 The maximum superconducting transition temperature found to date is 38 K in the Ba0.6K0.4Fe2As2. 10.1103/PhysRevLett.101.107006 18851249 2008PhRvL.101j7006R 0805.4630 Superconductivity at 38 K in the Iron Arsenide (Ba1−xKx)Fe2As2 Physical Review Letters 101 10 107006 2008 Rotter M. Tegel M. Johrendt D. 25876149 The microscopic description of superconductivity in the 122s is yet unclear. Iron-based superconductors: Timing is crucial Pickett, Warren E. Nature Physics 5 87–88 2009 10.1038/nphys1192 2 2009NatPh...5...87P https://zenodo.org/record/896844 Overview Ever since the discovery of high-temperature (High Tc) superconductivity in the cuprate materials, scientists have worked tirelessly to understand the microscopic mechanisms responsible for its emergence. To this day, no theory can fully explain the high-temperature superconductivity and unconventional (non-s-wave) pairing state found in these materials. 10.1038/nphys253 2006NatPh...2..138. Towards a complete theory of high TC Nature Physics 2 3 138–143 2006 1887/5125 119554620 free However, the interest of the scientific community in understanding the pairing glue for unconventional superconductors—those in which the glue is electronic, i.e. cannot be attributed to the phonon-induced interactions between electrons responsible for conventional BCS theory s-wave superconductivity—has recently been expanded by the discovery of high temperature superconductivity (up to Tc = 55 K) in the doped oxypnictide (1111) superconductors with the chemical composition XOFeAs, where X = La, Ce, Pr, Nd, Sm, Gd, Tb, or Dy. 10.1038/nature06972 18432191 https://www.researchgate.net/publication/5421101 Superconductivity at 43 K in an iron-based layered compound LaO1−xFxFeAs Nature 453 7193 376–8 2008 Takahashi H. Igawa K. Arii K. Kamihara Y. Hirano M. Hosono H. 2008Natur.453..376T 498756 10.1103/PhysRevLett.101.257003 19113744 2008PhRvL.101y7003H Neutron-Diffraction Measurements of Magnetic Order and a Structural Transition in the Parent BaFe2As2 Compound of FeAs-Based High-Temperature Superconductors Physical Review Letters 101 25 257003 2008 Huang Q. Qiu Y. Bao W. Green M. A. Lynn J. W. Gasparovic Y. C. Wu T. Wu G. Chen X. H. 0806.2776 119206773 The 122s contain the same iron-arsenide planes as the oxypnictides, but are much easier to synthesize in the form of large single crystals. There are two different ways in which superconductivity was achieved in the 122s. One method is the application of pressure to the undoped parent compounds. The second is the introduction of other elements (dopants) into the crystal structure in very specific ratios. There are two doping schemes: The first type of doping involves the introduction of holes into the barium or strontium varieties; hole doping refers to the substitution of one ion for another with fewer electrons. Superconducting transition temperatures as high as 38 K have been reported upon substitution of the 40% of the Ba2+ or Sr2+ ions with K+. The second doping method is to directly dope the iron-arsenide layer by replacing iron with cobalt. Superconducting transition temperatures up to ~20 K have been observed in this case. 10.1103/PhysRevLett.101.207004 19113371 2008PhRvL.101t7004L 0807.2223 Superconducting State in SrFe2−xCoxAs2 by Internal Doping of the Iron Arsenide Layers Physical Review Letters 101 20 207004 2008 Leithe-Jasper A. Schnelle W. Geibel C. Rosner H. 8645332 Unlike the oxypnictides, large single crystals of the 122s can be easily synthesized by using the flux method. 0901.4672 Structural, magnetic and superconducting phase transitions in CaFe2As2 under ambient and applied pressure Physica C: Superconductivity 469 9–12 404 Canfield, P. C. Paul C. Canfield 2009 Bud'ko Sergey Bud'ko Ni Kreyssig Goldman McQueeney Torikachvili Argyriou Luke Yu 10.1016/j.physc.2009.03.033 2009PhyC..469..404C 119281157 The behavior of these materials is interesting by that superconductivity exists alongside antiferromagnetism. Various studies including electrical resistivity, magnetic susceptibility, specific heat, 10.1103/PhysRevB.78.100504 0806.1043 2008PhRvB..78j0504K Magnetic and structural transitions in layered iron arsenide systems: AFe2As2 versus RFeAsO Physical Review B 78 10 100504 2008 Krellner C. Caroca-Canales N. Jesche A. Rosner H. Ormeci A. Geibel C. 119288375 NMR, 10.1103/PhysRevB.79.052504 0808.0744 2009PhRvB..79e2504B First-order magnetic transition in single-crystalline CaFe2As2 detected by 75As nuclear magnetic resonance Physical Review B 79 5 052504 2009 Baek S. -H. Curro N. J. Klimczuk T. Bauer E. D. Ronning F. Thompson J. D. 119004910 10.1103/PhysRevLett.102.227601 19658902 2009PhRvL.102v7601B NMR Investigation of Superconductivity and Antiferromagnetism in CaFe2As2 under Pressure Physical Review Letters 102 22 227601 2009 Baek S. -H. Lee H. Brown S. E. Curro N. J. Bauer E. D. Ronning F. Park T. Thompson J. D. 0903.2011 18061290 10.1088/1367-2630/11/7/075004 Low-energy spin dynamics in the antiferromagnetic phase of CaFe2As2 New Journal of Physics 11 7 075004 2009 Curro N. J. Dioguardi A. P. Aproberts-Warren N. Shockley A. C. Klavins P. 2009NJPh...11g5004C 0902.4492 14216790 neutron scattering, X-ray diffraction, Mössbauer spectroscopy, 10.1103/PhysRevB.78.020503 https://www.researchgate.net/publication/202152901 Spin-density-wave anomaly at 140 K in the ternary iron arsenide BaFe2As2 Physical Review B 78 2 020503 2008 Rotter M. Tegel M. Johrendt D. Schellenberg I. Hermes W. Pöttgen R. 2008PhRvB..78b0503R 0805.4021 118379843 and quantum oscillations 10.1088/0953-8984/21/32/322202 https://www.researchgate.net/publication/51239140 Quantum oscillations in antiferromagnetic CaFe2As2 on the brink of superconductivity Journal of Physics: Condensed Matter 21 32 322202 2009 Harrison N. McDonald R. D. Mielke C. H. Bauer E. D. Ronning F. Thompson J. D. 21693960 2009JPCM...21F2202H 0902.1481 12345149 have been performed for the undoped parent compounds, as well as the superconducting versions. Synthesis One of the important qualities of the 122s is their ease of synthesis; it is possible to grow large single crystals, up to ~5×5×0.5 mm, using the flux method. In a nutshell, the flux method uses some solvent in which the starting materials for a chemical reaction are able to dissolve and eventually crystallize into the desired compound. Two standard methods show up in the literature, each using a different flux. The first method employs tin, while the second uses the binary metallic compound FeAs (iron arsenide). 10.1088/0953-2048/21/12/125014 0807.0759 2008SuScT..21l5014L Growth and characterization of A1−xKxFe2As2 (A = Ba, Sr) single crystals with x = 0–0.4 Superconductor Science and Technology 21 12 125014 2008 Luo H. Wang Z. Yang H. Cheng P. Zhu X. Wen H. H. 2746754 Structural and magnetic phase transition The 122s form in the I4/mmm tetragonal structure. For example, the tetragonal unit cell of SrFe2As2, at room temperature, has lattice parameters a = b = 3.9243 Å and c = 12.3644 Å. The planar geometry is reminiscent of the cuprate high-Tc superconductors in which the Cu-O layers are believed to support superconductivity. High-temperature superconductivity in iron-based layered iron compounds Sadovskii, Mikhail V. Physics-Uspekhi 51 1201–1227 2008 10.1070/PU2008v051n12ABEH006820 12 2008PhyU...51.1201S 0812.0302 59490013 These materials undergo a first-order structural phase transition into the Fmmm orthorhombic structure below some characteristic temperature T0 that is compound specific. NMR experiments on the CaFe2As2 show that there is a first-order antiferromagnetic magnetic phase transition at the same temperature; in contrast, the antiferromagnetic transition occurs at a lower temperature in the 1111s. The high temperature magnetic state is paramagnetic, while the low temperature state is an antiferromagnetic state known as a spin-density-wave. Superconductivity Superconductivity has been observed in the 122s up to a current maximum Tc of 38 K in Ba1−xKxFe2As2 with x ≈ 0.4. Resistivity and magnetic susceptibility measurements have confirmed the bulk nature of the observed superconducting transition. The onset of superconductivity is correlated with the loss of the spin-density-wave state. The Tc of 38 K in Ba1−xKxFe2As2 (x ≈ 0.4) superconductor shows the inverse iron isotope effect. 10.1103/PhysRevLett.103.257003 20366277 2009PhRvL.103y7003S 0903.3515 Inverse Iron Isotope Effect on the Transition Temperature of the (Ba,K)Fe2As2 Superconductor Physical Review Letters 103 25 257003 2009 Shirage P. M. Kihou K. Miyazawa K. Lee C. H. Kito H. Eisaki H. Yanagisawa T. Tanaka Y. Iyo A. 44684501 Other compounds with 122 structure In addition to the iron arsenides, the 122 crystal structure plays an important role for other material systems as well. Three famous examples from the field of heavy fermions are CeCu2Si2 (the "first unconventional superconductor" discovered 1978),10.1103/PhysRevLett.43.1892 Superconductivity in the Presence of Strong Pauli Paramagnetism: CeCu2Si2 1979 Physical Review Letters 43 1892 Steglich F. J. Aarts Bredl C.D. Lieke W. Meschede D. Franz W. Schäfer H. 1979PhRvL..43.1892S 25 1887/81461 123497750 free URu2Si2 (which is also a heavy fermion superconductor but is the focus of active present research due to the so-called "hidden-order phase" below 17.5 K),10.1103/PhysRevLett.55.2727 Superconducting and Magnetic Transitions in the Heavy-Fermion System URu2Si2 1985 Physical Review Letters 55 2727–2730 Palstra T. T. M. Menovsky A. A. van den Berg J. Dirkmaat A. J. Kes P. H. Nieuwenhuys G. J. Mydosh J.A. 24 10032222 1985PhRvL..55.2727P https://pure.rug.nl/ws/files/14558353/1985PhysRevLettPalstra.pdf and YbRh2Si2 (one of the prime examples of quantum criticality).10.1038/nphys892 Quantum criticality in heavy-fermion metals 2008 Nature Physics 4 3 186 Gegenwart P. Si Q. Steglich F. 2008NatPh...4..186G 0712.2045 119086996 References Category:Superconductors Category:Correlated electrons Category:High-temperature superconductors Category:Iron compounds Category:Arsenides