High-tc superconductors based on feas compounds pdf file

It has also been found that some iron chalcogens superconduct. The extremely high magnetic field sensitivity of squids is based on the quantum interference effects described in chapter. The icddpdf coverage of the high tc superconductor and. Based on this feaslayered framework, the electronic band. Fermi surfaces contain sheets with both electronlike and holelike character in the doped feas based superconductors 20 and in the transuranic superconductor pucoga 5 21. In recent years, except for the discovery of several atypical superconductors, superconductor news has been mainly about novel ways to employ the new generation of ceramic superconductors, innovative. The synthesis and properties of lifeas, a hightc febased superconducting stoichiometric compound, are reported. Physics of ironbased high temperature superconductors. Ironbased high transition temperature superconductors national. It has turned out that there are many material varieties in iron based superconductors such as 7 parent materials,1111, 122, 111, 112, 245, 11 and.

The label high tc may be reserved by some authors for those with critical temperature greater than the boiling point of liquid nitrogen 77ak or a196aac. The synthesis and properties of lifeas, a high tc fe based superconducting stoichiometric compound, are reported. Following the laofeastype compounds, which served as a starting point in the study of feasbased hight c superconductors, bafe2as2, srfe2as2 129 and other afe2as2 a k, cs, sr. Development of conductor based on htsc powderintube technology pit.

In february 2008, an ironbased family of hightemperature superconductors was discovered. B, condensed matter 786 august 2008 with 158 reads. The ac losses in high tc superconductors can be described by the bean critical state model as long as the exponent n. Unlike the known isoelectronic undoped intrinsic feas compounds, lifeas does not show any spindensity wave behavior but exhibits. Reofeas 1111 oxypnictide superconductors several high tc superconductors have been discovered also in other fe based analogues compounds including ternary compound afe2as2 a is an alkali earth metal element such as sr and ba.

By synthesis of ba1xkxfe2as2 superconductivity was observed with a critical temperature tc38k. The icdd pdf coverage of the high tc superconductor and related compounds in the arcuo systems a ba, sr and ca, and r lanthanides and y volume 7 issue 3 winnie wongng. Synthesis and characterization of iron arsenic feas. Physical properties and models of electronic structure are analyzed for a new class of hightc superconductors which belong to ironbased layered compounds. Much like high tc copper oxides, superconductivity in the newly discovered the rareearth iron based oxide systems is derived from either electron or hole doping of their nonsuperconducting. Hightemperature superconductors are operatively defined as materials that behave as. The bcs theory bardeen, cooper, and schrieffer, 1957 17 was based. Bulk superconductivity at 21 k is observed after annealing the asprepared sample at 773 k for 40 h. The majority of hightemperature superconductors are ceramics materials. We seek for clues for unconventional superconductivity in the materials.

The discovery of a new class of hightemperature superconductors fe based layered compounds aroused a signi. Superconductors ceramic conductors are the socalled high t c superconductors, materials that lose their resistance at much higher critical temperatures than their metal alloy counterparts. Introduction since the discovery of superconductivity in. Fese is the simplest iron based superconductor but with the diverse properties. Hightc superconductors based on feas compounds request pdf. Cuprates, ferropnictides and ferrochalcogenides are three classes of unconventional high temperature superconductors, who share similar. The coexistence of superconductivity and spin density wave in smo 1x f x feas is theoretically studied using the model hamiltonian which contains bcs type superconductivity and spin density wave terms. The 122 iron arsenide unconventional superconductors are part of a new class of iron based superconductors. We have synthesized a new oxypnictide, ba2ti2fe2as4o, via a solidstate reaction under a vacuum. Physical properties and models of electronic structure are analyzed for a new class of high tc superconductors which belong to iron based layered compounds. High t c superconductivity in undoped thfeasn nature. High tc superconductors based on feas compounds yuri izyumov, ernst kurmaev auth. Superconductivity under high pressure in the binary compound cali 2 pdf file phys. An increased tc up of 56 k was reported in smo1xfxfeas 7.

The compound crystallizes in a bodycentered tetragonal lattice, which can be viewed as an intergrowth of bafe2as2 and bati2as2o, thus containing fe2as2 layers and ti2o sheets. A new iron based superconductor, ca,prfeas2, was discovered. Superconductivity is the set of physical properties observed in certain materials, wherein. This definition encompasses a wider variety of unconventional superconductors and is used in the context of theoretical models. Model the minimal electron model for feas based htsc follows from the crystal structure of these compounds 1 and band structure calculations, that show that the largest contribution to the electronic density of states near the fermi level give 3dstates of iron atoms 14, 23. Despite their variable chemical composition and differences in the crystal structure, these compounds possess similar physical. Some of the compounds have been known since 1995, and their semiconductive properties have been known and patented since 2006. A highangle annular darkfield image of 110 plane of la2cu5as3o2. Until 2008, only certain compounds of copper and oxygen socalled cuprates were known to have hts properties, and the term hightemperature superconductor was used interchangeably with cuprate superconductor for compounds such as bismuth strontium calcium copper oxide bscco and yttrium barium copper oxide. These new materials have tetragonal structure with the p4nmm space group, exactly like the feasbased compounds. Correlation properties and band structure of feas based superconductors vladimir kashurnikov, andrey krasavin.

Twenty years after the discovery of high temperature superconductors, practical. The structure was identified as the monoclinic system with space group p21m, composed of two capr planes, fe2as2 layers, and as2 zigzag chain layers. Exploring domelike tc in new superconductors is of interest to. The shorthand name 122 comes from their stoichiometry. Magnetic order in bafe2as2, the parent compound of the feas based superconductors in a new structural family article pdf available july 2008 with 179 reads how we measure reads.

This, the first volume on an emerging topic in materials science, examines in depth the physical properties and models of a new class of high tc superconductors which belong to iron based. But different from high tc cuprates that belong to strongly correlated charge transfer type mott compounds, the layered iron arsenide is an itinerant metalsemimetal. Examples of the use of superconductors in measurement techniques are squid magnetometers and infrared detectors. Iron based layered superconductor lao 1x f x feas x 0. Following the laofeastype compounds, which served as a starting point in the study of feas based high t c superconductors, bafe 2 as 2, srfe 2 as 2 129 and other afe 2 as 2 a k, cs, sr compounds have been synthesized, which under doping turned superconducting. Since their discovery 1, the classification of hightc superconductors has broadened.

Pressureinduced phase transitions and correlation between structure and superconductivity in iron based superconductor ceo0. Correlation properties and band structure of feasbased. The a15 type compounds crystallize in the cubic system, as shown in figure. Request pdf on jan 1, 2010, yuri izyumov and others published high tc superconductors based on feas compounds find, read and cite all the research you need on researchgate.

The simplest feasbased superconductor in structure is the afeas. Band structure of feasbased superconductors sciencedirect. Power applications of htsc what are possible applications. With the exception of the copper based high tc superconductors, this is the highest tc reported to date. Anomalous domelike superconductivity in re2 cu1xnix 5as3o2. Hightc superconductors based on feas compounds yuri. Magnetic and superconducting properties of feasbased high tc superconductors with gd article pdf available in jetp letters 905. Pdf the newly discovered high transition temperature superconductor. One of the most appropriate model for these compounds is the twoorbital model 9, 10 which is a typical. Pdf the synthesis and properties of lifeas, a hightc febased superconducting stoichiometric compound, are reported. The transition temperature tc exhibits a trapezoid shape dependence on the f content, with the highest tc of. Hightemperature superconductivity in ironbased materials arxiv.

Realspace pairing through charge transfer excitons in high tc cuprates. Hightc superconductors based on feas compounds ebook. Compounds of the afe2as2 a ba,sr,ca type springerlink. High tc superconductivity in cs3c60 compounds governed by local cs c60. Evidence for a sharp enhancement of spin fluctuations by nematic order abstract linear magnetor. The second is a rich variety in candidate materials and in pairing interaction. We report that a layered iron based compound laofeas undergoes superconducting transition under doping with f ions at the o2 site. Hightc superconductors based on feas compounds pdf free.

As well as copper based hightemperature superconductors htsc, these compounds have a layered structure. Compound smfeaso showed the evidence of superconductivity at. Hightc superconductors based on feas compounds springer. Unlike an ordinary metallic conductor, whose resistance decreases gradually as its temperature is lowered even down to near absolute zero, a superconductor has a. General theory of high t c superconductors 1 wileyvch. Single crystal xray studies reveal that it crystallizes in the tetragonal pbfcl type p4nmm with a3. Pdf hightc superconductivity in iron based pinictides and. Hightc superconductors based on feas compounds core. Simplified doping dependent phase diagram of cuprate superconductors for both electron n and hole p doping. Despite their variable chemical composition and differences in the crystal structure, these compounds. The highest tc in bulk ironbased superconductors is 55 k in.

Platelike crystals of the new phase were obtained, and its crystal structure was investigated by singlecrystal xray diffraction analysis. Potential uses of hightc superconductors are measurement techniques, electronics, magnet and energy applications. The copper oxide superconductors are characterized by crystal structures with one or more sheets of cuo 2, separated by insulating block layers. High tc superconductors based on feas compounds pp. Between 1986 and 1994 most advances in the field of superconductivity related to the discovery of new superconductor systems and compounds. Magnetic and superconducting properties of feasbased high. The phases shown are the antiferromagnetic af phase close to zero doping, the superconducting phase around optimal doping, and the. Superconductivity an overview sciencedirect topics.

High tc superconductors based on feas compounds pp 1254. Physics of iron based high temperature superconductors yuji matsuda department of physics, kyoto university, kyoto 6068502, japan abstract the discovery of high tc iron pnictide and chalcogenide superconductors has been one of the mostexciting recent developments in condensed matter physics. The surprising discovery of superconductivity in layered ironbased materials, with transition temperatures climbing as high as. Local antiferromagnetic exchange and collaborative fermi surface. Superconductivity is the set of physical properties observed in certain materials, wherein electrical resistance vanishes and from which magnetic flux fields are expelled. Given the itinerant character of charge carriers in ibs, superconductivity sc can be achieved via fermisurface tuning in two possible ways. Magnetic order close to superconductivity in the iron. Employing green function formalism, the expression for the spin density wave order parameter m and expression for spin density wave transition temperature t sdw is obtained. Any material exhibiting these properties is a superconductor. Pdf magnetic order in bafe2as2, the parent compound of. Most high t c ceramics are layered structures, with twodimensional copperoxygen sheets along which superconduction takes place. Ernst kurmaev physical properties and models of electronic structure are analyzed for a new class of high tc superconductors which belong to iron based layered compounds.