Quadrature skyrmions in two-dimensionally arrayed parametric resonators

Skyrmions are topological solitons in two-dimensional systems and have been observed in various physical systems. Generating and controlling skyrmions in artificial resonator arrays lead to novel acoustic, photonic, and electric devices, but it is a challenge to implement a vector variable with the chiral exchange interaction. Here, we propose to use quadrature variables, where their parametric coupling enables skyrmions to be stabilized. A finite-element simulation indicates that a stable acoustic skyrmion would exist in a realistic structure consisting of a piezoelectric membrane array.Comment: 22 pages, 10 figure

Thermal mixing between spin systems in Al2O3 by a resonant rf electric field

金沢大学教育学部理科教育Spin thermal mixing due to the irradiation of an rf electric field has been observed, for the first time, between a two-level system with m=2 and a dipolar system of Al27 nuclei in Al2O3. The thermal mixing is accomplished in a time much shorter than the spin-lattice relaxation time by applying strong rf electric field with amplitude of about 22 kV/cm at room temperature. Experimental results are sufficiently interpreted by the theory developed by assuming a concept of spin temperature in the rotating frame. A technique of double-quantum adiabatic demagnetization in the rotating frame is used in the experiments. © 1989 The American Physical Society

Rotary echoes due to magnetic dipolar interaction in a multi-level NMR system

金沢大学人間社会研究域学校教育系A new type of rotary echo which is due to magnetic dipolar interaction has been observed in a multi-level NMR system. From the echo-envelope decay we can estimate a second moment due to a part of dipolar interaction participating only in the resonant transition. © 1985