Origin of spin dependent tunneling through chiral molecules

The functionality of many biological systems depends on reliable electron transfer with minimal heating. Unlike man-made electric circuits, nature realizes electron transport via insulating chiral molecules. Here we include spin into the analysis of tunneling through these molecules, and demonstrate its importance for efficient transport. We show that the helical geometry induces robust spin filtering accompanied by, and intimately related to, strongly enhanced transmission. Thus, we resolve two key questions posed by transport measurements through organic molecules, demonstrating their common origin.