Unveiling Spin Selective Mechanism toward Very Large Spin Signals in Black Phosphorus 2D Semiconductor Spintronics Devices

Discovering an efficient spintronic semiconductor workhorse with dual host capabilities as a channel and spin valve barrier remains one of the most elusive endeavors toward the development of spin-logic circuits. Graphene paved the way for two-dimensional (2D) materials, yet engineering a controlled band gap in it remains a challenge. Black phosphorus (BP) was recently unveiled as a potential candidate in the realm of 2D semiconductors, with carrier mobilities among the largest reported for a 2D material and a low spin-orbit coupling reminiscent of graphene. Although promising spin transport properties have already been reported, their potential for tunneling and spin injection remains uncharted. Here, we unveil an unknown spin transport mechanism spin-split in k-space and report on corresponding high magnetoresistance spin signals up to 500% in BP based spin valves. Those findings are analyzed and discussed in light of a first-principles theoretical investigation showing BP's potential for spin filtering beyond its expected role of spin transport channel. This strongly supports BP's vision as an outstanding platform for spintronics, as it could become a versatile workhorse yet unavailable with any other semiconductor.