Coexistence of unconventional spin-orbit torque and in-plane Hall effect in a single ferromagnetic layer

TL;DR

This paper demonstrates the coexistence of two unconventional spin transport effects, CSOT and CIHE, in a high-symmetry CoPt ferromagnetic layer, enabling efficient room-temperature spintronic applications.

Contribution

It reveals that high-symmetry $C_{3v}$ materials can host multiple unconventional spin transport phenomena, challenging previous assumptions about symmetry constraints.

Findings

Achieved nearly 100% field-free perpendicular magnetization switching at room temperature.

Observed CIHE with dependencies matching CSOT, indicating a shared physical origin.

Confirmed symmetry analysis links both effects to the same underlying mechanism.

Abstract

The symmetry of a material fundamentally governs its spin transport properties. While unconventional spin transport phenomena have been predominantly explored in low-symmetry systems (e.g., $C_{1v}$ symmetry), high-symmetry crystals--which constitute the majority of industry-compatible materials--are generally expected to exhibit only conventional spin-transport behavior. Here, we report the coexistence of two unconventional spin transport effects, the crystal spin-orbit torque (CSOT) and the crystal in-plane Hall effect (CIHE), in a CoPt single ferromagnetic layer with $C_{3v}$ symmetry. Leveraging the CSOT, we achieve nearly 100% field-free perpendicular magnetization switching in a 6 nm CoPt layer at room temperature. Simultaneously, the CIHE observed in this material exhibits nearly identical dependencies on both current angle and growth temperature as the CSOT. Symmetry analysis confirms that both effects share a common physical origin. Our work not only establishes CoPt as a high-performance spin-orbit material, but also demonstrates that unconventional spin transport can be realized in high-symmetry systems, thereby opening a broad pathway for their application in practical spintronics.