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Acoustically driven ferromagnetic resonance (ADFMR) is a platform that enables efficient generation and detection of spin waves via magnetoelastic coupling with surface acoustic waves (SAWs). While previous studies successfully achieved ADFMR in ferromagnetic metals, there are only few reports on ADFMR in magnetic insulators such as yttrium iron garnet (Y3Fe5O12, YIG) despite more favorable spin wave properties, including low damping and long coherence length. The growth of high-quality YIG films for ADFMR devices is a major challenge due to poor lattice-matching and thermal degradation of the piezoelectric substrates during film crystallization. In this work, we demonstrate ADFMR of YIG thin films on LiNbO3 (LNO) substrates. We employed a SiOx buffer layer and rapid thermal annealing for crystallization of YIG films with minimal thermal degradation of LNO substrates. Optimized ADFMR device designs and time-gating measurements were used to enhance the ADFMR signal and overcome the intrinsically low magnetoelastic coupling of YIG. YIG films have a polycrystalline structure with an in-plane easy direction due to biaxial stresses induced during cooling after crystallization. The YIG device shows clear ADFMR patterns with maximum absorption for H ≈ 160 mT parallel to SAW propagation, which is consistent with our simulation results based on existing theoretical models. These results expand possibilities for developing efficient spin wave devices with magnetic insulators. 

Controlling magnetization dynamics is imperative for developing ultrafast spintronics and tunable microwave devices. However, the previous research has demonstrated limited electric-field modulation of the effective magnetic damping, a parameter that governs the magnetization dynamics. Here, we propose an approach to manipulate the damping by using the large damping enhancement induced by the two-magnon scattering and a nonlocal spin relaxation process in which spin currents are resonantly transported from antiferromagnetic domains to ferromagnetic matrix in a mixed-phased metallic alloy FeRh. This damping enhancement in FeRh is sensitive to its fraction of antiferromagnetic and ferromagnetic phases, which can be dynamically tuned by electric fields through a strain-mediated magnetoelectric coupling. In a heterostructure of FeRh and piezoelectric PMN-PT, we demonstrated a more than 120% modulation of the effective damping by electric fields during the antiferromagnetic-to-ferromagnetic phase transition. Our results demonstrate an efficient approach to controlling the magnetization dynamics, thus enabling low-power tunable electronics. 

Abstract Over the past decades, optical manipulation of magnetization by ultrafast laser pulses has attracted extensive interest. It not only shows intriguing fundamental science arising from the interactions between spins, electrons, phonons, and photons, but also manifests the potential to process and store data at a speed that is three orders of magnitude faster than the current technologies. In this paper, all‐optical helicity‐dependent switching (AO‐HDS) in hybrid metal–ferromagnet thin films, which consist of Co/Pt multilayers with perpendicular magnetic anisotropy and an Au film capping layer on the top, is experimentally demonstrated. The switching behaviors of the hybrid Co/Pt–Au material, with various laser repetition rates, scanning speeds, and fluencies, are systematically studied. In comparison with bare Co/Pt multilayers, the hybrid metal–ferromagnet thin films show pronounced AO‐HDS when the number of laser pulses per μm along the scanning direction gradually increases. In addition, the AO‐HDS effect is very robust against laser fluences. A possible mechanism is further proposed based on numerical simulations of the optomagnetic coupling model. These findings promise a new material system that exhibits stable AO‐HDS phenomena, and hence can transform future magnetic storage devices, especially with the addition of plasmonic nanostructures made of noble metals.