Figure 2: Metastable skyrmion lattice realized by magnetic- and electric-field cooling.
From: Transition to and from the skyrmion lattice phase by electric fields in a magnetoelectric compound
(a), The magnetic field dependence of the a.c. susceptibility χ' measured after magnetic-field (350 Oe) cooling under a field of +30 kV cm−1 and then scanning the magnetic field up and down (magenta symbols), and alternatively by decreasing the magnetic field from the ferromagnetic phase (black symbols). The measurement procedures are schematically illustrated in the inset. T and H represent the temperature and magnetic field, respectively. The magenta and black arrows represent the measurement procedures for the data shown in the main panel with the corresponding colour. The open magenta symbol in the main panel corresponds to the point indicated by the open magenta symbol in the inset. (b), The microwave spectra measured after the ME cooling (magenta) and without ME cooling (black). ΔS11 represents the microwave absorption coefficient. (inset) The magnetic field dependence of the resonance frequencies derived from the microwave spectra measured after the ME cooling. (c), The magnetic phase diagram including the metastable skyrmion state, under an electric field of +30 kV cm−1. Data points marked by magenta squares and triangles were determined via a.c. susceptibility measurements and microwave spectroscopy, respectively.
