Some of the members of the alkali fulleride family with stoichiometry a3c60 a alkali metal were found to become superconducting 4,5, with. Merohedral disorder and impurity impacts on superconductivity of. Superconductivity, electron paramagnetic resonance, and. Volume 43 number 20 28 may 2014 pages 73337632 dalton. In this family tc decreases with increasing inter fulleride separation, despite a continued. Sep, 2016 the prevailing feature of the theoretical literature on correlated fulleride superconductivity 19,4650 has been the necessity to implicate the dynamic jt effect in order to account for the robust experimental finding of a lowspin electronic ground state in the mottinsulating precursor state of the superconductors. Perspective on the phase diagram of cuprate hightemperature. The structure of solid c 60 grown from ch 2 cl 2 solution, which has not been. This approach culminated in the discovery of pressureinduced bulk superconductivity at 38 k in bodycentredcubic bcc structured a15 cs 3c 60 fig. The study of collapse of the electron band and the phonon vacuum is presented within the meanfield approximation. Size and symmetry of the superconducting gap in the f. Jahnteller orbital glass state in the expanded fcc cs3c.
Upper critical field reaches 90 tesla near the mott. Unconventional orbital ordering and emergent dimensional. Here, based on the realistic band structure for fulleride superconductors, we show that the recently proposed sosm state is characterized by a. Comparison of 87 rb t white squares and t black squares sedor fractions vs pulse spacing 2, at t80 k and applied field b8. Pdf strong superconductivity with local jahnteller phonons. In previous works, it has been argued that this state can be interpreted as a spontaneous orbitalselective mott state, in which the. The molecular a3c60 fulleride superconductors have a parent antiferromagnetic insulator in common with the atombased cuprates, but here, the c603 electronic structure controls the geometry and spin state. Unified understanding of superconductivity and mott transition in. A polaronic model of superconductivity in doped fulleride systems is presented. Fullerides are chemical compounds containing fullerene anions. One of the key quantities in any theory of superconductivity or metallicity is the finite densityofstates at the fermi level, n e f 3,4,8. Superconductivity in expanded fcc c603 fullerides journal. Theoretical analysis on cooperation of coulomb and. Fulleride superconductors where alkalimetal atoms are intercalated into c 60 molecules show superconductivity at temperatures of up to 38 k for cs 3 c 60.
Under high pressure, cs 3c 60 is a superconductor with t c 40k in fcc lattice as well as k 3c 60and rb 3c 60. It has a severely disordered antiferromagnetic ground state that becomes a superconductor with a high critical temperature, t. The normal and anomalous oneparticle greens functions are derived for a system with strong electron phonon coupling. This approach culminated in the discovery of pressureinduced bulk superconductivity at 38 k in bccstructured a15 cs 3c 60, the highest t c known for any molecular material. Kuramoto department of physics, tohoku university, sendai 9808578, japan email. Electronphonon interactions for fulleride superconductors s. To fully understand the impurity impact on fulleride superconductivity, we intentionally deposited fe atoms.
To access a cheminform abstract of an article which was published elsewhere, please select a full text option. H c2 of the fulleride superconductors na 2 csc 60, k 3 c 60, and rb x cs 3. May 06, 2016 universal scaling laws can guide the understanding of new phenomena, and for cuprate hightemperature superconductivity the influential uemura relation showed, early on, that the maximum critical. The reaction of c60 with alkali metals using both conventional solid state and low temperature solutionbased synthesis techniques has led to the production of fulleride salts with interesting structural and superconducting properties. It is rather unfortunate that 53 we do not have the spacetime nor the energy to include 54. Superconductivity an overview sciencedirect topics.
The metal cations are situated in the interstices of. The most expanded fccstructured alkali fulleride, cs. Structural and electronic properties of fulleride superconductors. We analyze fulleride superconductivity at experimental doping levels, treating the electronelectron and electronphonon interactions on an equal footing, and demonstrate that the jahnteller phonons create a local intramolecular pairing which is surprisingly resistant to the coulomb repulsion, despite the weakness of retardation in these lowbandwidth systems.
Lightinduced superconductivity in fullerenes maxplanck. Giant microwave absorption in fine powders of superconductors. The fulleride rb2inxgayc60 is a superconductor with tc 26 k. Understanding the relationship between the superconducting, the neighboring insulating, and the normal metallic state above t c is a major challenge for all unconventional superconductors. The sumo wrestler including the plate at the bottom weighs 202 kg. Cheminform is a weekly abstracting service, delivering concise information at a glance that was extracted from about 100 leading journals. This was the first example of a superconducting c 60 3 fulleride with nonfcc sphere packing this single nonfcc material has a higher t c than. Upper critical field reaches 90 teslas near the mott transition in alkalidoped fulleride superconductors. To a first approximation, the latter act simply as electron donors to the fullerene molecules and the molecular ions can be regarded as the lattice sites providing the electrons that in turn form the band structure of the solid. Everything from the physics and some of the history as well. Preparation and properties of alkalifulleride superconductors. The observation of superconductivity in orthorhombic sr 4 c 60, ba 4 c 60, and yb 2.
The next breakthrough in phononmediated superconductivity. Optimized unconventional superconductivity in a molecular. Superconductivity, electron paramagnetic resonance, and raman. Y means material x doped with element y, tc is the highest reported transition temperature in kelvins and hc is a critical magnetic field in tesla. Alkalifulleride superconductors with a maximum critical temperature tc of 40 k exhibit similar electronic phase diagram with unconventional hightc superconductors where the superconductivity resides proximate to a magnetic mottinsulating state. Superconductivity emerges for the a15 polymorph of the fulleride cs3c60 upon compression to a pressure of approximately 4 kbar.
Conductivity and superconductivity in c60 fullerides halinria. With the intercalation of water molecules in these fullerides, we predict that na3c60 becomes superconducting at a critical temperature of 47. Development of hts conductors with development in the area of hts materials, the next important stage is to put that material to use. Fulleride, synthesized by standard gaseous method, has primitive cubic lattice and is not a superconductor. Alkalidoped fullerides are unique exotic swave superconductors with maximum critical. Printed in austria london penetration depth and coherence peak in ammoniaintercalated fulleride superconductors m.
Reduction of 60fullerene in either the solid state or liquid ammonia with alkali or alkalineearth metals typically produces a series of salts called fullerides that are in general airsensitive rosseinsky 1998 see fulleride superconductors. Chiara tarantini is a staff research faculty member of the applied superconductivity center at the national high magnetic field laboratory, florida state university in tallahassee, florida, usa. Zhang and coworkers 27 first proposed that the doped alkali ion phonon mode produce a strong attraction for electrons on c 60 using a hubbard model to describe the superconductivity. Conductivity and superconductivity in c60 fullerides. To understand the underlying mechanisms for the evolution of h c2 0, we estimated unknown parameters that determine h p and supplementary fig. In this paper, we summarize earlier results on unconventional metallic fulleride phases as well as the newly discovered extended fulleride superconductors. Pdf doubleresonance nmr probes of structural distortions. A range of experiments has clarified the empirical requirements for fulleride superconductivity.
Superconductors have long been confined to niche applications, due to. Fulleride superconductors are threedimensional members of. The effect of carrier concentration on fulleride superconductivity is studied by x ray, raman, magnetization, and esr of two new cubic families. Theoretical analysis on cooperation of coulomb and electron. K 3 c 60 with a t c of 19 k has become the primary testing ground of fulleride superconductivity. Direct observation of fullgap superconductivity and. Jun 17, 2019 nonlocal order parameters in spacetime are proposed to characterize the unconventional orbitalselective conducting state in fulleride superconductors, called the jahnteller metal. Critical temperatures t c of the fulleride salts m 3 c 60. On the other hand, the c 60 molecules are orientationally disordered in the facecentered cubic trivalent corresponding author. Bcs means whether or not the superconductivity is explained within the. A unique sn inorganic polymer superconductor was also found in.
In these two cases, the transition temperature t c is 18 k and 29 k, respectively. Electron doping in the honeycomb bilayer superconductors zr. She was trained as a condensed matter physicist at the university of genoa, italy, and obtained her phd in 2007. Electronphonon pairing mechanism for superconductivity in. The alkali fullerides, a3c60 a alkali metal are molecular superconductors that undergo a transition to a magnetic mottinsulating state at. Metallic fulleride salts are composed of fulleride ions and cations, in most cases alkali or alkaline earth metal ions. Superconductivity up to 12 k in lidoped zrncl was found by yamanaka et al.
They combined three experiments on twodifferent morphologies microwaveabsorption and magnetic susceptibility x of powders,anddcresistivity offilms to assert superconductivity under unusually difficult, poorly controlled. The original article is trackable via the references option. Superconductivity,electronparamagneticresonance,and. Jun 19, 2009 unconventional properties of expanded fulleride superconductors predicted by this model include i an energy pseudogap in the normal phase. Photograph kindly supplied by the international superconductivity research center istec and nihonsumo kyokai, japan. This is also the first example of a superconducting c 60 3. Unconventional hightc superconductivity in fullerides.
Photograph kindly supplied by the international superconductivity research center istec and nihonsumo kyokai, japan, 1997. Alkali fulleride superconductors with a maximum critical temperature tc of 40 k exhibit similar electronic phase diagram with unconventional hightc superconductors where the superconductivity resides proximate to a magnetic mottinsulating state. Nov 23, 2000 the behavior of a3c60 superconductors at the large inter fulleride separation where the transition temperatures tc are highest is investigated by the synthesis and structural and electronic characterization of facecentered cubic fcc a3c60 compounds with the largest lattice parameters yet found. Under high pressure, is a superconductor with k in fcc lattice as well as and. This led to the discovery of new a 3 c 60 superconductors through varying the interfullerene separation e. Xray diffraction experiments revealed that the structure of solid c 60 was related to the solvent for crystallizing it.
Superconductivity, complete disappearance of electrical resistance in various. Fulleride superconductors 32 where alkalimetal atoms are intercalated into c 60 molecules show superconductivity at temperatures of up to 38ak for cs 3 c 60. The table below shows some of the parameters of common superconductors. Upper critical field reaches 90 teslas near the mott. However, distinct from cuprate compounds, which superconduct through twodimensional 2d cuo2 planes, alkali fullerides are attributed to the threedimensional 3d members of hightc family.
Intercalation of small molecules in alkali metal fullerides. Since then, superconductivity has been reported in fullerene doped with various other. Superconductivity from materials science to practical. The study of collapse of the electron band and the phonon vacuum is. Pdf strong superconductivity with local jahnteller. The recent report of a superconductivity onset near the critical temperature tc 18 k in potassiumdoped c60 raises questions concerning the composition and stability of the superconducting phase. Theoretical calculations of the electronphonon coupling, in particular for. A new kind of moleculebased superconductors was initiated by the discovery of superconductivity in alkalimetaldoped fullerene a 3 c 60, a representing either k or rb. The proximity of the mott transition, a typical solidstate effect, results in molecular crystals, where molecular spectroscopic methods prove very successful. Synthesis and structural analysis of nonstoichiometric. London penetration depth and coherence peak in ammoniaintercalated fulleride superconductors. However, distinct from cuprate compounds, which superconduct through twodimensional 2d cuo2 planes, alkali fullerides are attributed to the three. In the present thesis, i discuss some of the current advances in research in the field of the solid state science of fullerenes. Na 2 cs x c 60 0 superconductors, respectively, but with variable.
The constituent molecule c 60 has a socalled soccerball shape, and the crystal is composed of an fee structure. Superconductors were discovered in 1911 by heike kamerlingh onnes. Pdf london penetration depth and coherence peak in ammonia. The fulleride superconductors a3c60 a alkali provide another example in which rigidband doping gives a realistic picture 3 of a relatively high critical temperature tc superconductor.
Fulleride superconductors where alkalimetal atoms are intercalated into c 60 molecules, conducts around 38 k for cs 3c 60. Other potential superconducting systems with a high transition temperature ma y also include fulleride superconductors. Other potential superconducting systems with a high transition temperature ma y also include fulleride superconductors, or. Fulleride cs 3c 60, synthesized by standard gaseous method, has primitive cubic lattice and is not a superconductor. The efforts to synthesize fullerides with composition from to in a solvent toluol give amorphous or polymerized nonsuperconducting substances 2. Data sets are shown for c, 3 cs, and 85 rb t inset, where is the. We report on the properties of alkali fulleride superconductors prepared by the reactions of c 60 crystallized in several organic solvents toluene, cs 2, ch 2 cl 2 with a 1ka limetals. Nonlocal order parameters in spacetime are proposed to characterize the unconventional orbitalselective conducting state in fulleride superconductors, called the jahnteller metal. A3c60 a alkali metal superconductors adopt facecentred. List of superconductors wikipedia republished wiki 2. Using density functional theory we study the bonding in the a15 phase as a function of unit cell volume comparing it to that in the fcc polymorph. Feb 17, 2017 therefore, our results highlight the uniquely high h c2 measured in the fulleride superconductors that are cubic, and thus, 3d.
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