Transition to and from the skyrmion lattice phase by electric fields in a magnetoelectric compound

Abstract

Dissipation-less electric control of magnetic state variable is an important target of contemporary spintronics. The non-volatile control of magnetic skyrmions, nanometre-sized spin-swirling objects, with electric fields may exemplify this goal. The skyrmion-hosting magnetoelectric chiral magnet Cu2OSeO3 provides a unique platform for the implementation of such control; however, the hysteresis that accompanies the first-order transition associated with the skyrmion phase is negligibly narrow in practice. Here we demonstrate another method that functions irrespective of the transition boundary. Combination of magnetic-susceptibility measurements and microwave spectroscopy reveals that although the metastable skyrmion lattice is normally hidden behind a more thermodynamically stable conical phase, it emerges under electric fields and persists down to the lowest temperature. Once created, this metastable skyrmion lattice remains without electric fields, establishing a bistability distinct from the transition hysteresis. This bistability thus enables non-volatile electric-field control of the skyrmion lattice even in temperature/magnetic-field regions far from the transition boundary.

Probing dynamics in quantum materials with femtosecond X-rays

“…In multiferroic materials (anti-)ferromagnetic order and ferroelectricity coexist and interact by magnetoelectric coupling [92][93][94] 98 This material shows a complex phase diagram, with a rich number of competing phases that exhibit different magnetic structure, 99 where the application of an external magnetic field to the conical phase creates a skyrmion phase.…”

Increased lifetime of metastable skyrmions by controlled doping

“…Absorption peaks belonging to the helical (H±), conical (C±) and spin polarised (SP) magnetic structures are observed in the response of the sample after both FC and ZFC procedures. However, there is an additional absorption mode with positive B-slope in the FC data which we ascribe to the counter-clockwise (CCW) resonance of the metastable skyrmion lattice [20,30]. AC susceptibility, χ', measured at a range of temperatures for both FC and ZFC procedures is shown in Fig.…”

“…The limited extent of the equilibrium SkL phase in temperature and applied field therefore presents a significant obstacle which must be overcome. Metastable skyrmions, which have now been observed in the Co-Zn-Mn alloys [12][13][14], MnSi [15][16][17], Fe 0.5 Co 0.5 Si [18,19] and Cu 2 OSeO 3 [6,20], offer distinct advantages as a candidate for device application. They are observed to exist over a greatly extended field and temperature range, including at zero field and room temperature in Co 9 Zn 9 Mn 2 [13].…”

Ferromagnetic Resonance with Magnetic Phase Selectivity by Means of Resonant Elastic X-Ray Scattering on a Chiral Magnet

“…Such an in-depth understanding, however, may not be available when investigating novel materials [14][15][16] or when phenomena such as metastable states, glassy textures, phase coexistence, topological transitions, or pronounced history dependencies play a role [17][18][19][20][21][22][23][24][25].…”

“…1(e). Under field cooling, the skyrmion lattice may be frozen-in to lower temperatures as a metastable state [17,20,23,46]. As depicted in Fig.…”