Spin Photovoltaic Effect in Magnetic van der Waals Heterostructures

TL;DR

This paper demonstrates a spin photovoltaic effect in magnetic van der Waals heterostructures, revealing helicity-dependent photocurrents influenced by magnetic states and spin configurations, advancing the field of 2D spin-optoelectronics.

Contribution

It reports the first observation of spin photovoltaic effects in CrI3-based vdW heterostructures, linking magnetic order to helicity-dependent charge transfer and giant photo-magnetocurrent phenomena.

Findings

Photocurrent depends on light helicity and magnetic states.

Multiple magnetic field-induced plateaus in photocurrent.

Giant photo-magnetocurrent observed, approaching infinity at small bias.

Abstract

The development of van der Waals (vdW) crystals and their heterostructures has created a fascinating platform for exploring optoelectronic properties in the two-dimensional (2D) limit. With the recent discovery of 2D magnets, the control of the spin degree of freedom can be integrated to realize 2D spin-optoelectronics with spontaneous time-reversal symmetry breaking. Here, we report spin photovoltaic effects in vdW heterostructures of atomically thin magnet chromium triiodide (CrI3) sandwiched by graphene contacts. In the absence of a magnetic field, the photocurrent displays a distinct dependence on light helicity, which can be tuned by varying the magnetic states and photon energy. Circular polarization-resolved absorption measurements reveal that these observations originate from magnetic-order-coupled and thus helicity-dependent charge-transfer exciton states. The photocurrent displays multiple plateaus as the magnetic field is swept, which are associated with different spin configurations enabled by the layered antiferromagnetism and spin-flip transitions in CrI3. Remarkably, giant photo-magnetocurrent is observed, which tends to infinity for a small applied bias. Our results pave the way to explore emergent photo-spintronics by engineering magnetic vdW heterostructures.