Houston, TX 77005
4:00 p.m. Monday, Sept. 30, 2013
On Campus | Alumni
In its simplest form, a Weyl semi-metal breaks the time-reversal symmetry and consists of a pair of linearly dispersing, three dimensional, two-component fermions of opposite chirality, which are separated in the momentum space. The nodal points appear as the source and the sink of the Berry's gauge flux and the Weyl semi-metal phase marries the notions of the fermionic quantum criticality and the momentum space topology. Based on the specific-heat, the nuclear magnetic resonance and the thermal conductivity measurements, a singlet, chiral pairing of the form kz(kx ± i ky) has previously been proposed for URu2Si2. We show that in addition to the line node, this state also possesses chiral Weyl fermions around the Fermi surface poles. Therefore, URu2Si2 can provide the first experimental realization of a Weyl superconductor, where the chemical potential of the BdG quasiparticles is indeed pinned at the Dirac point. We show that this state possesses protected chiral surface states, which in turn give rise to anomalous spin, thermal Hall and magneto-electric effects, which can be utilized in probing the Weyl quasi-particles. The instabilities of the nodal line and the nodal points can lead to many competing density wave ordered states in the particle-hole channel. Employing a simple two-orbital, tight-binding model consisting of only ?7 states, we establish a set of density wave orders with wave-vector (0,0,2?/c), which is the nesting vector for the nodal lines. These density wave states can serve as the promising candidates for the enigmatic hidden ordered and the antiferromagnetic states.