Microwave pumping and spin dynamics in ferrimagnetic Y3Fe5O12 films and quantum hybrid structures

• Applicant: Dmitry Azamat, Ph.D.
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 547603784

The project aims to perform pulse-magnetic resonance and magneto-optical studies of thin YIG films (d<1m) and hybrid structures (ferrite-paramagnet structures) to clarify the following phenomena: 1. Non-linear magnon dynamics in ferrimagnetic Yttrium Iron Garnet (YIG) films. This part will focus on nonlinear processes used to excite short-wavelength spin waves (exchange spin waves). The establishment of coherent precession of magnetization for magnons with k = 0 will be investigated at a magnetic field oriented perpendicular to the film. Here, the long lived free induction (FID) signal in YIG films is probed to study the formation of Bose-Einstein condensation of magnons under non-resonant MW excitation (at different frequency shift of MW pulse from the resonance). In addition, the experiments on parametrically excited magnons in thin YIG films can be conducted to study the process of subsequent thermalization into the coherent magnon condensate. 2. Quantum amplification effect for bulk magnetostatic waves (MSW) waves in a hybrid structure of YIG and paramagnetic system which is represented by paramagnetic maser crystal such as GaN:Fe3+ and ZnO:Mn2+. Potential advantages and limitations can be considered in the case of ferrite-paramagnet structures when the microwave field of MSW waves interacts with the inverted spin system of ZnO:Mn2+ using optical pumping at liquid helium temperature. The possibility of the pumping generator in a YIG - maser crystal structure is under consideration.The results will be obtained by using of pulsed-magnetic resonance setup at X-band frequency of ~8 GHz given that the MSW frequency coincides with one of the Electron Spin Resonance (ESR) transitions. These data will be complemented by optical methods with micrometric spatial resolution for Brillouin light scattering measurements as well as by the optical detection of magnetic resonance (ODMR) technique.

• DFG Programme: WBP Position