Magnetoacoustic Relaxation by Cr²⁺ Jahn–Teller Centers Revealed from Elastic Moduli

Abstract

Magnetoacoustic investigations of the ZnSe:Cr2+ crystal with sphalerite structure, performed in Faraday geometry, show that there is a new channel of relaxation by the Cr2+ Jahn–Teller (JT) centers, induced by the magnetic field. A new method is worked out that allows to extract the relaxation time, either from the temperature changes of the elastic modulus in fixed magnetic field or from the magnetic field dependences at fixed temperatures. Application of both approaches to the imaginary part of the elastic modulus prove their efficiency and indicate that the magnetic field‐dependent relaxation rate reaches the magnitude of about 106 s−1 at T = 1.3 K.

Sub-lattice of Jahn-Teller centers in hexaferrite crystal

“…, and c T B , , respectively, and (ii) considering the magnetic field dependence of the relaxation time: τ τ = T B ( , ) 66 . It was shown 40 that magnetic field provided a new channel of relaxation.…”

“…We use the term dynamic modulus for the measured frequency-dependent modulus in contrast to the frequency independent isothermal c T and adiabatic c S moduli. Solution of the Zener equation 65 , by keeping only the first derivatives over time, gives expressions for the dynamic modulus c d 66 [Eqs. (22) or (23)].…”