  Helical magnetohydrodynamic turbulence with Hall effects is ubiquitous in
heliophysics and plasma physics, such as star formation and solar activities,
and its intrinsic mechanisms are still not clearly explained. Direct numerical
simulations reveal that when the forcing scale is comparable to the ion
inertial scale, Hall effects induce remarkable cross helicity. It then
suppresses the inverse cascade efficiency, leading to the accumulation of
large-scale magnetic energy and helicity. The process is accompanied by the
breaking of current sheets via filaments along magnetic fields. Using the
Ulysses data, the numerical findings are separately confirmed. These results
suggest a novel mechanism wherein small-scale Hall effects could strongly
affect large-scale magnetic fields through cross helicity.
