Erratum:Superconducting Single-Layer T-Graphene and Novel Synthesis Routes[Chin.Phys.Lett.36(2019)097401]

In Fig.4(a)of the article,the range ofλ(w)exhibited by the horizontal coordinate of the middle panel should be from 0 to 2,instead of 0 to 1.Figure 4(a)should be as follows:We note that this mistake does not affect the conclusion of our report,and apologize to readers for any inconvenience caused by our oversight.

Superconducting Single-Layer T-Graphene and Novel Synthesis Routes

Single-layer superconductors are ideal materials for fabricating superconducting nano devices.However,up to date,very few single-layer elemental superconductors have been predicted and especially no one has been successfully synthesized yet.Here,using crystal structure search techniques and ab initio calculations,we predict that a single-layer planar carbon sheet with 4-and 8-membered rings called T-graphene is a new intrinsic elemental superconductor with superconducting critical temperature(Tc)up to around 20.8 K.More importantly,we propose a synthesis route to obtain such a single-layer T-graphene,that is,a T-graphene potassium intercalation compound(C4 K with P4/mmm symmetry)is firstly synthesized at high pressure(>11.5 GPa)and then quenched to ambient condition;and finally,the single-layer T-graphene can be either exfoliated using the electrochemical method from the bulk C4 K,or peeled off from bulk T-graphite C4,where C4 can be obtained from C4 K by evaporating the K atoms.Interestingly,we find that the calculated Tc of C4 K is about 30.4 K at 0 GPa,which sets a new record for layered carbon-based superconductors.The present findings add a new class of carbon-based superconductors.In particular,once the single-layer T-graphene is synthesized,it can pave the way for fabricating superconducting devices together with other 2 D materials using the layer-by-layer growth techniques.

Composite topological nodal lines penetrating the Brillouin zone in orthorhombic AgF_(2)

It has recently been found that nonsymmorphic symmetries can bring many exotic band crossings.Here,based on symmetry analysis,we predict that materials with time-reversal symmetry in the space group of Pbca(No.61)possess rich symmetry-enforced band crossings,including nodal surfaces,fourfold degenerate nodal lines and hourglass Dirac loops,which appear in triplets as ensured by the cyclic permutation symmetry.We take Pbca AgF_(2) as an example in real systems and studied its band structures with ab initio calculations.Specifically,in the absence of spin-orbit coupling(SOC),besides the above-mentioned band degeneracies,this system features a nodal chain and a nodal armillary sphere penetrating the Brillouin zone(BZ).While with SOC,we find a new configuration of the hourglass Dirac loop/chain with the feature traversing the BZ,which originates from the splitting of a Dirac loop confined in the BZ.Furthermore,guided by the bulk-surface correspondence,we calculated the surface states to explore these bulk nodal phenomena.The evolution of these interesting nodal phenomena traversing the BZ under two specific uniaxial strains is also discussed.