In this Letter, we calculate the electron-phonon coupling of newly discovered superconductor LaFeAsO1-xFx using linear response. For pure LaFeAsO, calculated constant lambda=0.21 and logarithmic-averaged frequency omegaln=206 K give a maximum Tc 0.8 K, standard Migdal-Eliashberg theory. F-doped compounds, predict even smaller constants. To reproduce experimental Tc, 5-6 times larger would be needed. Our results indicate that is not sufficient to explain superconductivity in whole family...

Two hydrogen-rich materials, H$_3$S and LaH$_{10}$, synthesized at megabar pressures, have revolutionized the field of condensed matter physics providing first glimpse to solution hundred-year-old problem room temperature superconductivity. The mechanism underlying superconductivity in these exceptional compounds is conventional electron-phonon coupling. Here we describe recent advances experimental techniques, theory first-principles computational methods which made possible discoveries....

First-principles calculations of magnetic and, to a lesser extent, electronic properties the LaFeAsO-based superconductors show substantial apparent controversy, as opposed most weakly or strongly correlated materials. Not only do different reports disagree about quantitative values but there is also schism in terms interpreting basic physics interactions this system. In paper, we present systematic analysis using four first-principles methods and that while an unusual sensitivity...

In the last five years a large number of new high-temperature superconductors have been predicted and experimentally discovered among hydrogen-rich crystals, at pressures which are way too high to meet any practical application. this work, we report computational prediction hydride superconductor, LaBH$_{8}$, with T$_{c}$ 126 K pressure 50 GPa, thermodynamically stable above 100 dynamically down 40 an unprecedentedly low for high-T$_{c}$ hydrides. LaBH$_{8}$ can be seen as ternary...

Motivated by the recent report of room-temperature superconductivity at near-ambient pressure in N-doped lutetium hydride, we performed a comprehensive, detailed study phase diagram Lu-N-H system, looking for superconducting phases. We combined ab initio crystal structure prediction with ephemeral data-derived interatomic potentials to sample over 200,000 different structures. Out more than 150 structures predicted be metastable within ~50 meV from convex hull identify 52 viable candidates...

We substantiate by numerical and analytical calculations that the recently discovered superconductivity below 4 K in 3% boron-doped diamond is caused electron-phonon coupling of same type as ${\mathrm{M}\mathrm{g}\mathrm{B}}_{2}$, albeit three dimensions. Holes at top zone-centered, degenerate $\ensuremath{\sigma}$-bonding valence-band couple strongly to optical bond-stretching modes. The increase from two dimensions reduces mode softening crucial for ${T}_{c}$ reaching 40...

Raman and infrared transmission reflectivity measurements were carried out at room temperature high pressure (0--15 GPa) on ${\text{V}}_{1\ensuremath{-}x}{\text{Cr}}_{x}{\text{O}}_{2}$ compounds. spectra collected ambient conditions the $x=0.007$ 0.025 materials, which are characterized by different insulating monoclinic phases ($M3$ $M2$, respectively), while $x=0.025$ sample only. The present data compared with companion results undoped ${\text{VO}}_{2}$ [E. Arcangeletti et al., Phys. Rev....

Reports on sulfur hydride attaining metallicity under pressure and exhibiting superconductivity at temperatures as high 200 K have spurred an intense search for another room-temperature superconductor among hydrogen-rich compounds. Recently, compressed phosphorus (phosphine) was reported to metallize pressures above 45 GPa, reaching a superconducting transition temperature (${T}_{c}$) of 100 GPa. However, neither the exact composition nor crystal structure phase been conclusively determined....

We report ab-initio calculations of the superconducting properties two high-Tc sodalite-like clathrate yttrium hydrides, YH6 and YH10, within fully anisotropic ME theory, including Coulomb corrections. For both compounds we find almost isotropic gaps, resulting from a uniform distribution electron-phonon coupling over phonon modes electronic states mixed Y H character. The screening is rather weak, in Morel-Anderson pseudopotential mu*= 0:11, at odds with claims unusually large Tc lanthanum...

The recent reports on high-temperature superconductivity above 190 K in hydrogen sulfide at 200 GPa pressure, exceeding all previously discovered superconductors, has greatly invigorated interest dense hydrogen-rich solids. Here, we investigate a possible way to optimize the critical temperature these compounds by using first-principles linear-response calculations. We construct hypothetical alchemical atoms smoothly interpolate between elements of chalcogen group and study their bonding...

Abstract We report the theoretical prediction of two high-performing hydride superconductors BaSiH 8 and SrSiH . They are thermodynamically stable above pressures 130 174 GPa, respectively, metastable below that. Employing anharmonic phonon calculations, we determine minimum dynamical stability to be around 3 GPa for 27 , using fully anisotropic Migdal-Eliashberg theory, predict T c ’s 71 126 K, respectively. also introduce a method estimate lowest pressure synthesis, based on calculation...

Abstract Motivated by the recent claim of hot superconductivity with critical temperatures up to 550 K in La + x hydrides, we investigate high-pressure phase diagram compounds that may have formed experiment, using first-principles calculations for evolutionary crystal structure prediction and superconductivity. Starting from hypothesis observed T c be realized successive heating upon a pre-formed LaH 10 phase, examine plausible ternaries lanthanum, hydrogen other elements present diamond...

We report a high-throughput ab-initio study of the thermodynamic and superconducting proper- ties recently synthesized XB$_3$C$_3$ clathrates. These compounds, in which boron carbon form sponge-like network interconnected cages each enclosing central X atom, are attractive candidates to achieve high-Tc conventional superconductivity at ambient pressure, due simultaneous presence stiff B-C covalent tunable charge reservoir, provided by guest atom. Ternary compounds like CaB$_3$C$_3$,...

The extreme pressures required to stabilize the recently discovered superhydrides represent a major obstacle their practical application. In this paper, we propose novel route attain high-temperature superconductivity in hydrides at ambient pressure, by doping commercial metal borohydrides. Using first-principles calculations based on Density Functional Theory and Migdal-Eliashberg theory, demonstrate that Ca(BH$_4$)$_2$ moderate hole of 0.03 holes per formula unit, obtained through partial...

We calculate the effect of local magnetic moments on electron-phonon coupling in BaFe$_{2}$As$_{2}+\delta$ using density functional perturbation theory. show that magnetism enhances total by $\sim 50%$, up to $\lambda \lesssim 0.35$, still not enough explain high critical temperature, but strong have a non-negligible superconductivity, for instance, frustrating with spin fluctuations and inducing order parameter nodes. The enhancement comes mostly from renormalization matrix elements. also...

We report low-temperature specific heat measurements for high-quality single crystalline KFe2As2 (T_c about 3.5 K). The investigated zero-field data yields an unusually large nominal Sommerfeld coefficient gamma_n of 94(3) mJ/mol K^2 which is however significantly affected by extrinsic contributions as evidenced a sizable residual linear and various theoretical considerations including also analysis Kadowaki-Woods relations. Then should be classified weak to intermediately strong coupling...

With the aim of manipulating mechanical properties recently discussed two-dimensional material MXene, we investigate effect alloying. We consider substitutional doping B and V at Ti C sites ${\mathrm{Ti}}_{2}\mathrm{C}$. Calculations quantities such as in-plane stiffness, Young's modulus, critical strain through rigorous first-principles technique establish that is highly effective in improving elastic properties. Oxygen passivation B-doped ${\mathrm{Ti}}_{2}\mathrm{C}$ addition to improved...

A powerful approach to analysing quantum systems with dimensionality $d>1$ involves adding a weak coupling an array of one-dimensional (1D) chains. The resultant quasi-one-dimensional (q1D) can exhibit long-range order at low temperature, but are heavily influenced by interactions and disorder due their large anisotropies. Real q1D materials therefore ideal candidates not only provoke, test refine theories strongly correlated matter, also search for unusual emergent electronic phases. Here...

Among elemental compounds, the high-pressure superconducting phase diagram of phosphorus is one most complex. Resistivity measurements and $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ superconductivity calculations reported in this paper solve for first time open controversies on anomalous trends; forming a single, consistent scenario multiple metastable structures which coexist beyond...

Motivated by the recent discovery of near-room temperature superconductivity in high-pressure superhydrides, we investigate from first principles superconducting phase diagram ternary Ca-B-H system, using ab initio evolutionary crystal structure prediction, and Density Functional Perturbation Theory. We find that below 100 GPa all stable weakly metastable phases are insulating. This pressure marks appearance several new chemically-forbidden on hull stability, onset metalization...

The quantum nature of the hydrogen lattice in superconducting hydrides can have crucial effects on material's properties. Taking a detailed look at dynamic stability recently predicted BaSiH

We report the discovery of superconductivity below 1.65(6) K in Sr-intercalated graphite SrC6, by susceptibility and specific heat (Cp) measurements. In comparison with CaC6, we found that anisotropy upper critical fields for SrC6 is much reduced. The Cp anomaly at Tc smaller than BCS prediction indicating an anisotropic superconducting gap similar to CaC6. significantly lower as compared CaC6 can be understood terms "negative" pressure effects, which decreases electron-phonon coupling both...

Abstract This paper explains the multi‐orbital band structures and itinerant magnetism of iron‐pnictide chalcogenide superconductors. We first describe generic structure a single, isolated FeAs layer. Use its Abelian glide‐mirror group allows us to reduce primitive cell one unit. For lines points high symmetry in corresponding large, square Brillouin zone, we specify how one‐electron Hamiltonian factorizes. From density‐functional theory, for observed LaOFeAs, generate set eight Fe d As p...

Superconductivity at high-pressures has attracted considerable interest after the report of a record critical temperature (${T}_{c}$) 203 K in sulfur hydride (H${}_{3}$S) 200 GPa. In this work, authors predict several novel lithium-sulfur compounds high pressure using evolutionary crystal structure prediction techniques and investigate their superconducting properties with density functional linear response calculations. The calculations reveal an intrinsic correlation between...

It is a honor to write contribution on this memorial for Sandro Massidda. For both of us, at different stages in our lives, was first and foremost friend. We admired his humble, playful profound approach life physics. In we describe the route which permitted meet long-standing challenge solid state physics, i.e. room temperature superconductivity. less than 20 years critical conventional superconductors, last century had been widely believed be limited 25 K, raised from 40 K MgB2 265 LaH10....