The concept was first introduced by Tandberg in their TB-6X 1960s, and more widely used by Akai and their US brand, Roberts.
Additionally, the record head is used to introduce a tape bias signal that improves frequency response.
Additionally, the heads are arranged so the combination of the two signals results in a small "dead zone" directly past the recording head where high frequency signals are blanked out.
This prevents subsequent high frequency signals from interfering with those just recorded, by the time they exit the dead zone they are too far from the head to be overwritten.
For proper results, cross-field recording needed high quality tapes, to ensure the oxide layer was thick enough to allow the bias signal to imprint on the deeper levels of the oxide without reaching the front surface.