Search for New Superconductors: an Electro-Magnetic Phase Transition in an Iron Meteorite Inclusion at 117 K

Abstract

The discovery of superconductivity in pnictides and iron chalcogenides inspires the search for new iron based superconducting phases. Iron-rich meteorites present a unique opportunity for this search, because they contain a broad range of compounds produced under extreme growth conditions. We investigated a natural iron sulfide based materials (Troilite) inclusion with its associated minerals in the iron meteorite Tlacotepec.Tlacotepec formed in an asteroidal core under high pressure and at high temperature over millions of years, while insoluble sulfur rich materials segregated into inclusions during cooling along with included minerals. The search for superconductivity in these heterogeneous materials requires a technique capable of detecting minute amounts of a superconducting phase embedded in a non-superconducting matrix. We used Magnetic Field Modulated Microwave Spectroscopy (MFMMS), a very sensitive, selective, and non-destructive technique, to search for superconductivity in heterogeneous systems.Here, we report the observation of an electro-magnetic phase transition at 117 K that causes a MFMMS-response typical of a superconductor. A pronounced and reproducible peak together with isothermal magnetic field sweeps prove the appearance of a new electromagnetic phase below 117 K. This is very similar to the characteristic response due to flux trapping in a granular superconductor with a short coherence length. Although the compound responsible for the peak in the MFMMS-spectra was not identified, it is possibly an iron sulfide based phase, or another material heterogeneously distributed over the inclusion. Main Text:The discovery of iron-based superconductors, a new class of superconducting compounds with an unconventional pairing mechanism, has rekindled the interest in the search for new superconducting materials [1][2][3]. Superconducting iron chalcogenides like undoped β-FeSe [4], Fe(Se 1-x Te x ) [5,6] or S-substituted FeTe [7] are of particular interest.The superconducting transition temperature T c of FeSe can be significantly increased by applying high external pressure [8]. Several attempts were made to increase the transition temperature either by high pressure, high temperature synthesis, or by substituting selenium with sulfur that has a smaller atomic radius [9,10]. However, in this study we search for superconductivity in naturally occurring materials instead of synthesizing new compounds. This approach has two advantages: First, we can investigate materials that have crystallized under very extreme conditions like very long cooling time, high

Calculation of a magnetic force acting on small superconducting celestial bodies

“…Naturally occurring superconducting phases were recently found by Wampler et al [1] in the samples from two meteorites-iron meteorite Mundrabilla and ureilite GRA 95205 using magnetic field modulated microwave spectroscopy [2]. Some other hints were observed earlier by Guenon et al [3]. This discovery prompts to analyse the possible effect of superconductivity on the behaviour of celestial bodies and quantify the strength of a magnetic force acting on possible superconducting bodies in space.…”

Nanocrystalline Iron Monosulfides Near Stoichiometry

“…A similar phenomenon has been reported in iron pyrite, where atomic defects, either in the bulk or on the surface, narrow the gap substantially 21 – 23 . Given that iron-sulfur based compounds are poised to have a tremendous impact in technologies including energy storage 65 , photovoltaics 48 , high temperature superconductors 7 , 9 , 24 , and catalysis 66 , it becomes evident that more research is required to determine structure-property relationships in these materials, particularly with regard to even small degrees of off-stoichiometry.…”

“…Ricci and Bousquet predict that troilite should have a large room-temperature magnetoelectric effect, while Guénon et al . have explored troilite as a candidate for a non-tetragonal high T c iron based superconductor 8 , 24 . In situ , troilite samples are exclusively found in meteorites as a minority phase, and are thus seldom without impurities and defects.…”

Electronic and magnetic properties of two-dimensional of FeX (X = S, Se, Te) monolayers crystallize in the orthorhombic structures

“…But, the hexagonal FeTe is far less magnetic than the hexagonal FeSe and FeS. 21,22 Due to their fascinating magnetic properties, iron chalcogenides are a promising candidate for lithiumion battery, 23,24 energy storage and conversion, 25,26 the spintronic and magnetic semiconductor. 27,28 For low dimensional structures, thin film and monolayer, FeS and FeSe were familiar as superconductors.…”