Engineering topics

Zhang, Zhizhi

Publications and source records attributed to Zhang, Zhizhi.

5 records

DOE OSTI2021

Phase-resolved electrical detection of coherently coupled magnonic devices

We demonstrate the electrical detection of magnon-magnon hybrid dynamics in yttrium iron garnet/Permalloy (YIG/Py) thin film bilayer devices. Direct microwave current injection through the conductive Py layer excites the hybrid dynamics consisting of the uniform mode of Py and the first standing spin wave (n=1) mode of YIG, which are coupled via interfacial exchange. Both the two hybrid modes, with Py- or YIG-dominated excitations, can be detected via the spin rectification signals from the conductive Py layer, providing phase resolution of the coupled dynamics. The phase characterization is also applied to a nonlocally excited Py device, revealing the additional phase shift due to the perpendicular Oersted field. Our results provide a device platform for exploring hybrid magnonic dynamics and probing their phases, which are crucial for implementing coherent information processing with magnon excitations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2021

Direct Imaging of Resonant Phonon-Magnon Coupling

Detection of phonons is critical for research on the interconversion between resonantly coupled magnons and phonons. Here we report the direct visualization of the resonant coupling of magnons and phonons by microfocused Brillouin light scattering on the Ni/Li Nb O 3 hybrid heterostructure. The static patterns of surface acoustic wave phonons, originating from the interference between the incident wave ψ 0 (A 0 , k, φ 0 ) and reflected wave ψ 1 (A 1 , - k, φ 1 ), can be modulated by magnetic field due to the magnon-phonon coupling. By analyzing the information of phonons obtained from Brillouin spectroscopy, the properties of the magnon system (Ni film), e.g., ferromagnetic resonance field and resonance linewidth, can be determined. The results provide spatially resolved information about phonon manipulation and detection in a coupled magnon-phonon system.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2020

Experimental parameters, combined dynamics, and nonlinearity of a magnonic-opto-electronic oscillator (MOEO)

We report the construction and characterization of a comprehensive magnonic-opto-electronic oscillator (MOEO) system based on 1550-nm photonics and yttrium iron garnet (YIG) magnonics. The system exhibits a rich and synergistic parameter space because of the ability to control individual photonic, electronic, and magnonic components. Taking advantage of the spin wave dispersion of YIG, the frequency self-generation as well as the related nonlinear processes becomes sensitive to the external magnetic field. Besides being known as a band-pass filter and a delay element, the YIG delay line possesses spin wave modes that can be controlled to mix with the optoelectronic modes to generate higher-order harmonic beating modes. With the high sensitivity and external tunability, the MOEO system may find usefulness in sensing applications in magnetism and spintronics beyond optoelectronics and photonics.

47 OTHER INSTRUMENTATION↗

DOE OSTI2020

Phonon Transport Controlled by Ferromagnetic Resonance

The resonant coupling of phonons and magnons is important for the interconversion of phononic and spin degrees of freedom. We study the phonon transmission in LiNbO 3 manipulated by the dynamic magnetization in a Ni thin film. It is observed that the phonons can be absorbed strongly through resonant magnon-phonon coupling, which is realized by our modifying the magnon-phonon coupling within the Ni itself as well as our optimizing the interfacial coupling between Ni and LiNbO 3 . The line shapes of phonon transmission are further investigated considering the magnon-phonon interconversion in the elastically driven ferromagnetic resonance process. The results promote unique routes for phonon manipulation and detection in the presence of magnetization dynamics.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2020

Coherent Spin Pumping in a Strongly Coupled Magnon-Magnon Hybrid System

Here, we experimentally identify coherent spin pumping in the magnon-magnon hybrid modes of yttrium iron garnet/permalloy (YIG/Py) bilayers. By reducing the YIG and Py thicknesses, the strong interfacial exchange coupling leads to large avoided crossings between the uniform mode of Py and the spin wave modes of YIG enabling accurate determination of modification of the linewidths due to the dampinglike torque. We identify additional linewidth suppression and enhancement for the in-phase and out-of-phase hybrid modes, respectively, which can be interpreted as concerted dampinglike torque from spin pumping. Furthermore, varying the Py thickness shows that both the fieldlike and dampinglike couplings vary like 1/$\sqrt{𝑡_{Py}}$, verifying the prediction by the coupled Landau-Lifshitz equations.

ferromagnetic resonance↗