Easy-axis ferromagnetic chain on a metallic surface

ALEJANDRO M. LOBOS; MIGUEL A. CAZALILLA

JOURNAL OF PHYSICS CONDENSED MATTER

IOP PUBLISHING LTD

Lugar: Londres; Año: 2013 vol. 25 p. 94008 - 94008

0953-8984

The phases and excitation spectrum of an easy-axis ferromagnetic chain of S=1/2 magnetic impurities built on the top of a clean metallic surface are studied. As a function of the (Kondo) coupling to the metallic surface and at low temperatures, the spin chain exhibits a quantum phase transition from an Ising ferromagnetic phase with long-range order to a paramagnetic phase where quantum fluctuations destroy the magnetic order. In the paramagnetic phase, the system consists of a chain of Kondo singlets where the impurities are completely screened by the metallic host. In the ferromagnetic phase, the excitations above the Ising gap are damped magnons, with a finite lifetime arising due to the coupling to the substrate. We discuss the experimental consequences of our results to spin-polarized electron energy loss spectroscopy, and we finally analyze possible extensions to spin chains with S > 1/2.