Electric field-tunable ferromagnetism in a van der Waals semiconductor up to room temperature.

Abstract

Ferromagnetic semiconductors, coupling charge transport and magnetism via electrical means, show great promise for spin-based logic devices. Despite decades of efforts to achieve such co-functionality, maintaining ferromagnetic order at room temperature remains elusive. Here, we address this long-standing challenge by implanting dilute Co atoms into few-layer black phosphorus through atomically-thin boron nitride diffusion barrier. Our Co-doped black phosphorus-based devices exhibit ferromagnetism up to room temperature while preserving its high mobility (~ <math xmlns="http://www.w3.org/1998/Math/MathML"> <msup><mrow><mn>1000</mn> <mi>cm</mi></mrow> <mrow><mn>2</mn></mrow> </msup> <msup><mrow><mi>V</mi></mrow> <mrow><mo>-</mo> <mn>1</mn></mrow> </msup> <msup><mrow><mi>s</mi></mrow> <mrow><mo>-</mo> <mn>1</mn></mrow> </msup> </math> ) and semiconducting characteristics. By incorporating ferromagnetic Co-doped black phosphorus into magnetic tunnel junction devices, we demonstrate a large tunnelling magnetoresistance that extends up to room temperature. This study presents a new approach to engineering ferromagnetic ordering in otherwise nonmagnetic materials, thereby expanding the repertoire and applications of magnetic semiconductors envisioned thus far.