Abstract

Bistable Characteristics of a Nonlinear Magnetoacoustic Hematite Resonator

Y.Fetisov, I.Lukoshnikov (Moscow Institute of Radioengineering, Electronics and Automation, Moscow, Russia)

e-mail: fetisov@orc.ru

Magneto-elastic coupling in easy-plane antiferromagnetic hematite crystals (a-Fe2O3) produces a giant effective acoustic nonlinearity [1]. The nonlinearity results in a power dependent shift of the acoustic resonance frequency and a bistable behavior of hematite resonators [2]. This paper describes quantitative results of experimental investigation of a bistable hematite resonator. Measurements were carried our using a disk resonator (6 mm in diameter and 0.8 mm thick) in the 0.3-0.6 MHz frequency band at input power levels up to 100 mW. At increasing power the bistability was observed in the transmitted power vs. frequency response as well as in the phase vs. frequency response. A possibility was demonstrated to switch the resonator between low-power and high-power stable states by changing the input signal level. Being included in the feedback oscillator loop, the bistable magnetoacoustic resonator provided oscillation of radio-pulses with a period of 10-40 ms. Characteristics of the resonator are well described by the model of dispersion type bistability. The research was supported by Award VZ-010-0, U.S. CRDF and R.F. Ministry of Education. 1. V.I. Ozhogin, V.L.Preobrazhensky, J. Magn.& Magn. Mater.,1991, v.100, p.554. 2. F. Merkelov, S. Masson, V. Preobrazhensky et al, Abstracts of the 17-th International Congress on Acoustics, vol.1, Physical Acoustics, Rome, Sept. 2002.

Section : 2