Ultrahigh Exchange Bias Field/Coercive Field Ratio in In Situ Formed Two-Dimensional Magnetic Te-Cr 2 O 3 /Cr 5 Te 6 Heterostructures

The exchange bias (EB) effect is a fundamental magnetic phenomenon, in which the exchange bias field/coercive field ratio (|H /H |) can improve the stability of spintronic devices. Two-dimensional (2D) magnetic heterostructures have the potential to construct low-power and high-density spintronic devices, while their typically air unstable and |H /H | lesser, limiting the possibility of applications. Here, 2D Cr Te nanosheets have been systematically synthesized with an in situ formed ≈2 nm-thick Te doped Cr O layer (Te-Cr O ) on the upper surface by chemical vapor deposition (CVD) method. The strong and air stable EB effect, achieving a |H /H | of up to 80% under an ultralow cooling field of 0.01 T, which is greater than that of the reported 2D magnetic heterostructures. Meanwhile, the uniformity of thickness and chemical composition of the Te-Cr O layer can be controlled by the growth conditions which are highly correlated with the EB effect of 2D Te-Cr O /Cr Te heterostructures. First-principles calculations show that the Te-Cr O can provide uncompensated spins in the Cr O , thus forming strong spin pinning effect. The systematical investigation of the EB effect in 2D Te-Cr O /Cr Te heterostructures with high |H /H | will open up exciting opportunities in low-power and high-stability 2D spintronic devices.