Spin texture of time-reversal symmetry invariant surface states on W(110)

We find in the case of W(110) previously overlooked anomalous surface states having their spin locked at right angle to their momentum using spin-resolved momentum microscopy. In addition to the well known Dirac-like surface state with Rashba spin texture near the Gamma-point, we observe a tilted Dirac cone with circularly shaped cross section and a Dirac crossing at 0.28 x Gamma(N) over bar within the projected bulk band gap of tungsten. This state has eye-catching similarities to the spin-locked surface state of a topological insulator. The experiments are fortified by a one-step photoemission calculation in its density-matrix formulation