Creation of a Nanoskyrmion Lattice in the Fe/Ir(111) System Using a Voltage Pulse

Magnetic ultrathin films grown on heavy metal substrates often exhibit rich spin structures due to the competition between various magnetic interactions such as Heisenberg exchange, DzyaloshinskiiMoriya interaction and higher-order spin interactions. Here we employ spin-polarized scanning tunneling microscopy to study magnetic nanoskyrmion phase in Fe monolayer grown on Ir(111) substrate. Our observations show that the formation of nanoskyrmion lattice in the Fe/Ir(111) system depends sensitively on the growth conditions and various nonskyrmion spin states can be formed. Remarkably, the application of voltage pulses between the tip and the sample can trigger a nonskyrmion-to-skyrmion phase transition. Such a phase transition is determined by the total injected energy during the voltage pulse suggesting that there exists a potential barrier between a metastable nonskyrmion spin state and a true skyrmion ground state. The creation of a skyrmion lattice at the nanoscale will be useful to design skyrmion-based spintronic devices.