Giant magnetization canting due to symmetry breaking in zigzag Co chains on Ir(001)

Abstract

We demonstrate a canted magnetization of biatomic zigzag Co chains grown on the (5 × 1) reconstructed Ir(001) surface using density functional theory (DFT) calculations and spin-polarized scanning tunneling microscopy (SP-STM) experiments. It is observed by STM that biatomic Co chains grow in three different structural configurations. Our DFT calculations show that they are all in a ferromagnetic (FM) state. Two chain types possess high symmetry due to two equivalent atomic strands and an easy magnetization direction that is along one of the principal crystallographic axes. The easy magnetization axis of the zigzag Co chains is canted away from the surface normal by an angle of 33°. This giant effect is caused by the broken chain symmetry on the substrate in combination with the strong spin-orbit coupling of Ir. SP-STM measurements confirm the stable FM order of the zigzag chains with a canted magnetization.

Colloquium: Atomic spin chains on surfaces

“…Such zigzag chains are realized when Co is deposited and they were studied using SP-STM. Similar to the case of the Co chain attached to the step edge of Pt(997), the Co biatomic chains on (5×1)-Ir(001) are ferromagnetic with an easy magnetization axis canted with respect to the surface normal (Dupé et al, 2015).…”

“…In SP-STM measurements on biatomic Fe chains on (5 × 1)-Ir(001) at 8 K a magnetic signal is only detected (Menzel et al, 2012)). (d) Symmetry equivalent biatomic zigzag chains on the (5×1)-Ir(001) surface as realized by Co (taken from (Dupé et al, 2015)). (e) SP-STM topography colorized with the simultaneously obtained differential conductance signal of biatomic Fe and Co chains grown on (5 × 1)-Ir(001); whereas the Fe chain on the left switches its magnetization frequently the magnetic spin spiral ground state of the right Fe chain (see sketch) is fixed by direct exchange coupling to the adjacent ferromagnetic Co chain (adapted from (Menzel et al, 2012)).…”

Magnetization reversal of ferromagnetic nanoparticles induced by a stream of polarized electrons

“…This technique was demonstrated to allow both the diagnosis of magnetization vectors as well as study their effect readily. A magnetic STM chromium tip indicated double chains of atoms, consisting of a few tens of atoms located on the surface of Ir (001) with (5 Â 1) reconfiguration and its characteristic magnetization vector [10]. This result established the change of chain magnetization.…”

Magnetic properties of the finite-length biatomic chains in the framework of the single domain-wall approximation

“…Finally, we find the reversal time of the magnetization τ weak of the biatomic chains in a weak coupling approximation by substituting either (11) and (12) for the chains of type A, or (15) and (16) for the chains of type B. Note that in the limit of |J | → 0 the value of τ weak tends to 2τ 1 , where τ 1 is the reversal time of the magnetization of the single-atomic chain in the absence of external fields calculated by the formula (70).…”