Ultrahigh Exchange Bias Field/Coercive Field Ratio in In Situ Formed Two‐Dimensional Magnetic Te‐Cr2O3/Cr5Te6 Heterostructures

Abstract The exchange bias (EB) effect is a fundamental magnetic phenomenon, in which the exchange bias field/coercive field ratio (|H EB /H C |) 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 EB /H C | lesser, limiting the possibility of applications. Here, 2D Cr 5 Te 6 nanosheets have been systematically synthesized with an in situ formed ≈2 nm‐thick Te doped Cr 2 O 3 layer (Te‐Cr 2 O 3 ) on the upper surface by chemical vapor deposition (CVD) method. The strong and air stable EB effect, achieving a |H EB /H C | 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 2 O 3 layer can be controlled by the growth conditions which are highly correlated with the EB effect of 2D Te‐Cr 2 O 3 /Cr 5 Te 6 heterostructures. First‐principles calculations show that the Te‐Cr 2 O 3 can provide uncompensated spins in the Cr 2 O 3 , thus forming strong spin pinning effect. The systematical investigation of the EB effect in 2D Te‐Cr 2 O 3 /Cr 5 Te 6 heterostructures with high |H EB /H C | will open up exciting opportunities in low‐power and high‐stability 2D spintronic devices.