Spin-Conserving Resonant Tunneling in Twist-Controlled WSe₂-hBN-WSe₂ Heterostructures

We investigate interlayer tunneling in heterostructures consisting of two tungsten diselenide (WSe₂) monolayers with controlled rotational alignment, and separated by hexagonal boron nitride. In samples where the two WSe₂ monolayers are rotationally aligned we observe resonant tunneling, manifested by a large conductance and negative differential resistance in the vicinity of zero interlayer bias, which stem from energy- and momentum-conserving tunneling. Because the spin-orbit coupling leads to coupled spin-valley degrees of freedom, the twist between the two WSe₂ monolayers allows us to probe the conservation of spin-valley degree of freedom in tunneling. In heterostructures where the two WSe₂ monolayers have a 180° relative twist, such that the Brillouin zone of one layer is aligned with the time-reversed Brillouin zone of the opposite layer, the resonant tunneling between the layers is suppressed. These findings provide evidence that, in addition to momentum, the spin-valley degree of freedom is also conserved in vertical transport.