Qiang-Hua Wang

Experimental Detection of a Majorana Mode in the core of a Magnetic Vortex inside a Topological Insulator-Superconductor Bi 2 Te 3 / NbSe 2 Heterostructure

Majorana fermions have been intensively studied in recent years for their importance to both fundamental science and potential applications in topological quantum computing1,2. Majorana fermions are predicted to exist in a vortex core of superconducting topological insulators3. However, they are extremely difficult to be distinguished experimentally from other quasiparticle states for the tiny energy difference between Majorana fermions and these states, which is beyond the energy resolution of most available techniques. Here, we overcome the problem by systematically investigating the spatial profile of the Majorana mode and the bound quasiparticle states within a vortex in Bi2Te3/NbSe2. While the zero bias peak in local conductance splits right off the vortex center in conventional superconductors, it splits off at a finite distance ~20nm away from the vortex center in Bi2Te3/NbSe2, primarily due to the Majorana fermion zero mode. While the Majorana mode is destroyed by reducing the distance between vortices, the zero bias peak splits as a conventional superconductor again. This work provides strong evidences of Majorana fermions and also suggests a possible route to manipulating them.

Functional renormalization group and variational Monte Carlo studies of the electronic instabilities in graphene near 1/4 doping

We study the electronic instabilities of near 1/4 electron doped graphene using the singular-mode functional renormalization group, with a self-adaptive

Triplet pairing and possible weak topological superconductivity inBiS2-based superconductors

k

Majorana modes in a topological insulator/s-wave superconductor heterostructure

mesh to improve the treatment of the van Hove singularities, and variational Monte Carlo method. At 1/4 doping the system is a chiral spin-density wave state exhibiting the anomalous quantized Hall effect. When the doping deviates from 1/4, the

Competing electronic orders on kagome lattices at van Hove filling

{d}_{{x}^{2}\ensuremath{-}{y}^{2}}+i{d}_{xy}

Topological superconducting phase in the vicinity of ferromagnetic phases

Cooper pairing becomes the leading instability. Our results suggest that near 1/4 electron or hole doping (away from the neutral point) the graphene is either a Chern insulator or a topoligical superconductor.

Testing the d*(x2-y2)-wave pairing symmetry by quasiparticle interference and Knight shift in BiS2-based superconductors

We show that the newly discovered BiS

Anderson impurity in a helical metal

_2

Unrestricted renormalized mean field theory of strongly correlated electron systems

-based superconductors may have a dominant triplet pairing component, in addition to a subdominant singlet component arising from the spin-orbital coupling. The pairing respects time-reversal symmetry. The dominant triplet gap causes gap sign changes between the spin-split Fermi pockets. Within a pocket, the gap function respects

Impurity and interface bound states in dx2-y2 + idxy and px + ipy superconductors

d^*_{x^2-y^2}