Four discrete Hall resistance states in single-layer Fe film for quaternary memory devices

We report the realization of four distinct magnetic states using single layers of Fe at room temperature. When the Fe film was grown on the vicinal surface of GaAs, the fourfold-symmetric magnetization along crystallographic direction give rise to four distinct Hall resistance values due to the different combination of planar and anomalous Hall effects for the given direction. Each Hall resistance state can be written reproducibly by the sequence of field pulses and was remained constant at the written state for more than 2 h, which brings the idea of a quaternary memory device much closer to practical implementation.