Enantiospecific Magnetoconductance Asymmetry in a Racemic Conglomerate Driven by Surface-Assisted Symmetry Breaking

Chirality-induced spin selectivity (CISS) has been predominantly demonstrated in enantiopure systems, while racemic mixtures are considered spin-inactive due to the cancellation of opposite enantiomeric contributions. Here, we demonstrate that surface-assisted symmetry breaking activates CISS in racemic systems. A racemic bis -helical [1]benzothieno[3,2- b ]benzothiophene ( BTBT ) derivative ( Rac -1 ) spontaneously segregates into homochiral ( M, M ) and ( P, P ) domains, forming a two-dimensional (2D) racemic conglomerate directly visualized by scanning tunneling microscopy (STM). Scanning tunneling spectroscopy (STS) reveals enantiospecific magnetoconductance asymmetry (EMA) within individual homochiral domains at room temperature, reaching +(40 ± 5)% for ( P, P ) domains and −(35 ± 10)% for ( M, M ) domains when the ferromagnetic Co layer is magnetized perpendicular to the substrate plane. Magnetization-direction-dependent STS measurements show that EMA is reduced from ∼35% for out-of-plane to