Experimental observation of spin-exchange-induced dimerization of an atomic one-dimensional system

Using low-temperature scanning tunneling microscopy, we demonstrate a one-dimensional system that undergoes a charge-density-wave (CDW) instability on a metallic substrate. For our measurements we utilize a self-assembled monatomic chain of Co atoms aligned by the steps on a vicinal Cu(111) surface. We assign the measured CDW instability to ferromagnetic interactions along the chain. We show that though the linear arrayed dimers are not electronically isolated, they are magnetically independent, and hence can potentially serve as a binary spin-memory system.