  It is proposed that the new generation of spintronics should be ideally
massless and dissipationless for the realization of ultra-fast and
ultra-low-power spintronic devices. We demonstrate that the spin-gapless
materials with linear energy dispersion are unique materials that can realize
these massless and dissipationless states. Furthermore, we propose four new
types of spin Hall effects which consist of spin accumulation of equal numbers
of electrons and holes having the same or opposite spin polarization at the
sample edge in Hall effect measurements, but with vanishing Hall voltage. These
new Hall effects can be classified as (quantum) anomalous spin Hall effects.
The physics for massless and dissipationless spintronics and the new spin Hall
effects are presented for spin-gapless semiconductors with either linear or
parabolic dispersion. New possible candidates for Dirac-type or parabolic type
spin-gapless semiconductors are demonstrated in ferromagnetic monolayers of
simple oxides with either honeycomb or square lattices.
