Gate-tunable spin valve effect in Fe3GeTe2-based van der Waals heterostructures

Magnetic tunnel junctions (MTJs), a prominent type of spintronic device based on the spin valve effect, have facilitated the development of numerous spintronic applications. The technical appeal for the next-generation MTJ devices has been proposed in two directions: improving device performance by utilizing advanced two-dimensional (2D) ferromagnetic materials or extending device functionalities by exploring the gate-tunable magnetic properties of ferromagnets. Based on the recent development of 2D magnets with the ease of external stimuli, such as electric field, due to their reduced dimensions, reliable prospects for gate-tunable MTJ devices can be achieved, shedding light on the great potential of next-generation MTJs with multiple functionalities for various application environments. While the electrical gate-tunable MTJ device is highly desirable for practical spintronic devices, it has not yet been demonstrated. Here, we demonstrate the experimental realization of a spin valve device by combining a vertical Fe3GeTe2/h-BN/Fe3GeTe2 MTJ with an electrolyte gate. The magnetoresistance ratio (MR ratio) of 36% for the intrinsic MTJ confirms the good performance of the device. By electrolyte gating, the tunneling MR ratio of Fe3GeTe2/h-BN/Fe3GeTe2 MTJ can be elevated 2.5 times, from 26% to 65%. Importantly, the magnetic fields at which the magnetoresistance switches for the MTJ can be modulated by electrical gating, providing a promising method to control the magnetization configuration of the MTJ. Our work demonstrates a gate-tunable MTJ device toward the possibility for gate-controlled spintronic devices, paving the way for performing 2D magnetism manipulations and exploring innovative spintronic applications.