Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session D52: Magnetization and Spin Dynamics II: YIG-based and AFM MaterialsRecordings Available
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Sponsoring Units: GMAG Chair: Rico Schoeneman, Los Alamos National Laboratory Room: McCormick Place W-475A |
Monday, March 14, 2022 3:00PM - 3:12PM |
D52.00001: Auto-oscillations in noncollinear two-magnet hybrid nanostructures Shirash Regmi, Bassim Arkook, Christopher Safranski, Rodolfo Rodriguez, Jing Shi, Igor Barsukov Combining insulating and metallic ferromagnets in hybrid heterostructures adds novel functionalities by harnessing the virtues of both material systems [1,2]. Here, we use bilayers of yttrium iron garnet (YIG) and nickel (Ni) and fabricate nanowire devices using e-beam lithography and ion-milling. The magnetoresistive phenomena of Ni allow us to access static and dynamic states of the heterostructure [2-4]. We investigate hybrid magnons with magnetic field applied perpendicular to the device plane and identify aligned and non-aligned modes. By supplying electric currents, we observe microwave emission from the nanowire, corresponding to auto-oscillations of the non-aligned mode. The signal is symmetric in both field and current polarity [2], indicating an excitation by thermal spin currents. Such thermally-driven auto-oscillations in heterostructures with noncollinear magnetization open avenues for spin-orbitronic functionalization of hybrid magnetic systems and would benefit neuromorphic computing [5] and quantum magnonics. |
Monday, March 14, 2022 3:12PM - 3:24PM |
D52.00002: Nonequilibrium Three-magnon Scattering of Ferromagnetic Resonance in YIG Thin Films Alex Hamill, Tao Qu, Paul A Crowell, Randall H Victora In thin films, large ferromagnetic resonance (FMR) amplitudes excite the first order Suhl instability, a nonlinear regime where FMR undergoes three-magnon scattering to two modes of half the frequency and wavevectors ±k. Despite its applicability to magnon BECs, magnonics, and other fields, a comprehensive study and formal model of the nonequilibrium behavior is lacking. We have developed an experimental technique for sensitive detection of the time-evolution of the FMR amplitude over five orders of magnitude in power, which provides a highly comprehensive view of the three-magnon scattering process. Applying this technique to 3μm thick YIG thin films, we observe strong agreement with results from micromagnetic simulations. We also developed a semianalytical model to describe the nonequilibrium three-magnon scattering process. This model shows quantitative agreement with the experiment and simulations, including the timescales of the instability (~100ns-1us), a new secondary nonlinear regime with MHz-frequency oscillatory behavior, and the scaling of this oscillation frequency with power. At high powers, we find broadening of the oscillation spectra correlated to the simulations’ onset of higher-order scattering processes. Additional findings will also be discussed. |
Monday, March 14, 2022 3:24PM - 3:36PM |
D52.00003: Spin-wave amplification using spin-orbit torque in ultra-thin BiYIG/Pt microscopic waveguide Hugo Merbouche, Boris Divinskiy, Diane Gouéré, Aya El Kanj, Romain Lebrun, Vincent Cros, Paolo Bortolotti, Vladislav E Demidov, Sergej O Demokritov, Abdelmadjid Anane In this work we report the first experimental observation of the amplification of rf-excited propagating spin-waves (SW) based on spin-orbit torque (SOT), in a 500nm wide Bi1YIG/Pt waveguide using micro Brillouin light scattering spectroscopy. |
Monday, March 14, 2022 3:36PM - 3:48PM |
D52.00004: Probing strong magnon-magnon coupling in a magnonic hybrid system Dinesh Wagle, Yi Li, Mojtaba Taghipour Kaffash, Sergi Lendinez, Mohammad Tomal Hossain, Valentyn Novosad, Matthias Benjamin Jungfleisch Magnon based hybrid systems have attracted increasing interest due to their potential application in coherent information processing. We demonstrate electrical and optical detection of hybrized magnon-magnon dynamics in exchange-coupled nm-thick yttrium iron garnet/permalloy (YIG/Py) bilayer devices using spin rectification and Brillouin light scattering at room temperature. The uniform mode in the conductive Py layer and the first perpendicular standing spin-wave modes in the insulating YIG layer are coupled through interfacial exchange. We observe a magnon-magnon coupling strength of 9 mT for YIG(84 nm)/Py(10 nm). The introduction of a thin insulating SiO$_2$ layer between YIG and Py strongly suppresses the hybrid dynamics. Our work explores hybrid magnonic dynamics that are important in the implementation of coherent data processing. |
Monday, March 14, 2022 3:48PM - 4:00PM |
D52.00005: Travelling photons-mediated coherent and dissipative couplings in long-distance cavity magnonics Ying Yang, Wei Lu, Can-Ming Hu Engineering strong coupling between systems is essential for many phenomena of quantum physics and technology, especially in long distance without field overlap. We demonstrate the indirect coherent and dissipative couplings in a spatially separated cavity magnonic system mediated by travelling photons. The system is constructed by placing a dielectric resonator (cavity photon mode) and an Yttrium Iron Garnet sphere (magnon mode) along the transmission line that provides travelling photons, with a distance much larger than the resonance wavelength to avoid direct coupling. The long-distance coupling between cavity and magnon modes is highly tunable with position and could be manipulated to be nonreciprocal. At a fixed distance of (n+1/2)*wavelength, we observe coherent coupling for the left-going travelling photons and dissipative coupling for the right-going travelling photons. A general model of indirect magnetic dipole-dipole interaction is derived to explain our results, which enhances our understanding of long-distance coupling and nonreciprocity. Our engineered approach to indirect coherent and dissipative coupling through travelling photons provides a way to establish nonreciprocal links among spatially separated systems to build networks of oscillators, which opens a range of opportunities for remote control that can be easily switched between coherent and dissipative coupling mechanisms. |
Monday, March 14, 2022 4:00PM - 4:12PM |
D52.00006: Direct imaging of strong photon-magnon coupling in a planar geometry Mojtaba Taghipour Kaffash, Dinesh Wagle, Sergi Lendinez, M. Benjamin Jungfleisch Recently, photon-magnon (MP) coupling has attracted great attention due to the coherent information exchange, critical for quantum-information applications. Essential in this regard is the miniaturization of the microwave source and the magnetic medium for information transduction applications. |
Monday, March 14, 2022 4:12PM - 4:24PM |
D52.00007: Structural and multiferroic properties of doubly ordered perovskites NaLnNiWO6 (Ln = Dy-Lu) Ravi Shankar P N, and A. Sundaresan* School of Advanced Materials, and Chemistry and Physics of Materials Unit, Jakkur P.O., Bangalore 560064, India Email: ravishankar@jncasr.ac.in Ravi S P N
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Monday, March 14, 2022 4:24PM - 4:36PM |
D52.00008: Spin pumping in d-wave superconductor/ferromagnet hybrids Santiago J Carreira, David Sanchez-Manzano, Myoung-Woo Yoo, Kevin Seurre, Victor Rouco, Anke Sander, Jacobo Santamaria, Abdelmadjid Anane, Javier E Villegas Spin-pumping across d-wave superconductors such as YBa2Cu3O7-d (YBCO) in ferromagnet/superconductor interfaces provides a new playground for the study of spin polarized supercurrents due to the d-wave nature of the superconducting gap. Here we use wideband ferromagnetic resonance to study spin-pumping effects in bilayers that combine a soft metallic Ni80Fe20 (Py) ferromagnet and YBCO. We evaluate the spin conductance in YBCO by analyzing the magnetization dynamics in Py. We find that the Gilbert damping exhibits a drastic drop as the heterostructures are cooled across the normal-superconducting transition and that well below the critical temperature the damping depends on the surface morphology of the YBCO. In particular, an upturn of the damping appears at low temperatures and can be explained by the large density of quasiparticle bound states characteristic of d-wave superconductivity. Our hypothesis is that those states are accessible via YBCO crystallites at the surface, which directly exposes the YBCO ab plane to the interface with the ferromagnet. These findings open the path for tuning the spin pumping efficiency by engineering the YBCO surface, for example by growing YBCO in different crystallographic directions. |
Monday, March 14, 2022 4:36PM - 4:48PM |
D52.00009: Strong coupling of antiferromagnetic resonance in YFeO3 and Fabry-Perot type cavity modes at above 0.5 THz Marcin Bialek, Jean-Philippe Ansermet We investigate the strong coupling of antiferromagnetic resonance and THz electromagnetic cavity modes. Since polariton modes are hybrid light-matter states, they have properties that can be used in quantum devices, as shown in many physical systems where such coupling was achieved. Recently, magnon-polaritons are intensively researched in ferromagnetic materials in the microwave range. There is an interest in obtaining THz magnon-polaritons with antiferromagnetic materials that would allow for spin quantum effects to be observed at much higher frequencies than with ferromagnets. However, there are only a few reports on strong magnon-photon coupling at THz frequencies, which is mostly due to difficulty in manufacturing high quality factor cavities. Here, we report an investigation of a room temperature system with yttrium ferrite (YFeO3) single crystal of a 0.5 mm thickness placed on a copper mirror. We measured reflection from this system using a monochromatic continuous wave spectrometer operating in the range of 0.5-0.75 THz that is based on frequency extenders to a vector network analyser. Measured reflection spectra show modes of a Fabry-Perot type cavity created by the mirror and the sample-air boundary. With rising temperature, these modes are interacting with the quasi-antiferromagnetic mode of YFeO3, that is softening with rising temperature. This strong interaction is manifested by avoided crossings in frequency-temperature dependence, with the splitting between the polariton modes of about 20 GHz. Obtained results show clearly that Farby-Perot type cavities can be used to obtain strong magnon-photon coupling, which is an important improvement that can allow for further investigations of THz strong coupling in antiferromagnetic materials. |
Monday, March 14, 2022 4:48PM - 5:00PM |
D52.00010: An electronic noise study of temperature and current-induced magnetization dynamics Vineetha S Bheemarasetty, Kang Wang, Yiou Zhang, Gang Xiao We investigate the magnetization-induced noise dynamics from microscopic thermal fluctuations and applied currents in a magnetic thin film using electronic noise measurements, complemented by magnetic imaging. We detect distinct fluctuation characteristics of the electronic noise signal resulting from the current-induced magnetic domain nucleation and propagation in addition to the thermally-induced domain-wall oscillatory behavior in different frequency domains. Both these dynamics indicate a dependence on the magnetic configuration. Our investigation of all magnetic configurations created in the magnetic thin film including magnetic multidomains and skyrmions gives us a complete electronic noise description of the microscopic and fluctuating magnetization dynamics. |
Monday, March 14, 2022 5:00PM - 5:12PM Withdrawn |
D52.00011: Time-domain terahertz spectroscopy and its application to antiferromagnetic resonances Joseph P Avenoso, Weipeng Wu, M. Benjamin Jungfleisch, Lars Gundlach Antiferromagnets have shown promise for spintronics and quantum computing due to their high resonance frequencies in terahertz range. It is therefore important to have an experimental technique that can measure these resonances and their properties with high spectral resolution. Time-domain terahertz spectroscopy (TDTS) is a popular technique for measuring phonon and plasmon resonances, and can be extended to measuring magnons in a spectral range inaccessible to other methods such as FTIR or microwaves. While terahertz emission from magnetic heterostructures has been the primary focus of THz spintronics, terahertz absorption is promising for measuring antiferromagnetic magnon resonances. A common limiting factor for THz absorption spectroscopy is the Fabry-Pérot (FP) reflections that cause oscillations in the absorption spectra and thus reduce the resolution. Experimental and computational methods to remove these oscillations from the spectra are discussed for the antiferromagnetic insulator NiO. The 8 GHz resolution of the TDTS system resolves a magnon frequency shift that depends on the crystallographic orientation, which was previously unresolved due to the FP reflections. Furthermore, the temperature-dependence of the magnon resonances is investigated. Optical pump-terahertz probe spectroscopy is introduced and the time-resolved coupling mechanisms of resonance excitations is discussed. |
Monday, March 14, 2022 5:12PM - 5:24PM |
D52.00012: Magnetic properties and spin dynamics of (Zn0.15Cu1.85)V2O7 Ganatee Gitgeatpong, Yang Zhao, Kittiwit Matan, Pakornsak Saeun, Taku J Sato, Pharit Piyawongwatthana Magnetic properties of (Zn0.15Cu1.85)V2O7 have been investigated on powder and single crystal samples using magnetization and neutron scattering measurements. The nuclear structure of (Zn0.15Cu1.85)V2O7 resembles that of monoclinic β-Cu2V2O7. Based on DFT calculations [PRB 82, 144416 (2010)], the spin couplings of these systems were found to topologically form a 2D honeycomb spin network. Combined magnetic susceptibility and power neutron diffraction suggest that the spins are co-aligned antiparallel along the crystallographic c-axis. Quantum Monte Carlo simulations based on the proposed honeycomb model with the dominant 5th and 6th nearest-neighbor exchange interactions provide a good fit to the magnetic susceptibility data. Inelastic neutron scattering data show the absence of nonreciprocal magnons, which were observed in the cousin phase of the noncentrosymmetric magnet α-Cu2V2O7 [PRL 119, 047201 (2017)]. The disappearance of the nonreciprocal magnons in (Zn0.15Cu1.85)V2O7 and presumably β-Cu2V2O7 can be explained by the absence of the Dzyaloshinskii-Moriya interaction. In addition, the magnon dispersion is consistent with the proposed honeycomb spin model. |
Monday, March 14, 2022 5:24PM - 5:36PM |
D52.00013: Spin singlet-triplet excitations in a spin-1/2 honeycomb magnet Cu5SbO6 Chairote Piyakulworawat, Kittiwit Matan, Yang Zhao, Pharit Piyawongwatthana, Taku J Sato, Masaki Ageishi, Suttipong Wannapaiboon, Kenji Nakajima The S = 1/2 honeycomb lattices have long been recognized as a potential host for a wide spectrum of appealing magnetic ground states. Of particular interest is the so-called valence bond solid state with singlet-triplet excitations (triplons), which is possibly realized in the delafossite-derived compound Cu5SbO6. Magnetic susceptibility measurements on single crystals indicate that Cu5SbO6 exhibits a spin gap with an average energy gap of 16 meV. To investigate the magnetic excitations in more details, we performed inelastic neutron scattering experiments on both powder and single-crystal samples. The results clearly show three magnetic excitation branches two of which are non-dispersive triplon bands. The existence of the two triplon bands with different energy gaps is ascribed to the presence of the Dzyaloshinski-Moriya (DM) interaction between the next-nearest-neighbor Cu2+ ions in the hexagon. The coupling between nearest-neighbor Cu2+ ions is likely ferromagnetic and a center of inversion between the nearest-neighbor spins prohibits the DM interaction. It is found that the z-component of the DM interaction splits the triplet states with ms = 0 and ms = ±1. At 2.8 K, the triplet states with ms = ±1 is associated with the excitation at 15 meV and those with ms = 0 with 18 meV. In addition to the non-dispersive bands, a relatively dispersive branch is also visible, which could be due to a non-vanishing dimer-dimer interaction. |
Monday, March 14, 2022 5:36PM - 5:48PM |
D52.00014: Magnon dynamics studied by two-pulse THz coherent spectroscopy Chuankun Huang, JIGANG Wang THz multi-dimensional coherent spectroscopy (THz-MDCS) is a powerful coherent spectroscopy tool to study spin coherence in complex materials. Although THz-MDCS has been applied in magnetic materials, it has not been able to measure high order magnon correlations exceeding third order until this work. Here, we measure coherent nonlinear responses of various magnonic systems using THz-MDCS. The unique high harmonic and wave mixing peaks are resolved up to 6th order, which reveals complicated spin interaction and multi-magnon excitations. We further achieve coherent control of the magnon dynamics by changing the two-pulse separation. Our results show THz MDCS spectroscopy is a powerful tool to study vast coherent nonlinear processed and spin correlations in complex magnetic systems. |
Monday, March 14, 2022 5:48PM - 6:00PM |
D52.00015: Strain evolution of spin-wave in BiFeO3 thin film Taehun Kim, Jiemin Li, Yanhong Gu, Jonathan Pelliciari, Yuwei Liu, Zhihai Zhu, Yuefeng Nie, Valentina Bisogni BiFeO3 is one of the most famous multiferroic systems, due to its strong magneto‐electric coupling at room temperature promising large potential for future devices. The coupling enables that the magnetic state can be tuned on demand by an external electric field [1], and by local lattice distortion, strain [2]. A spin-wave, the excitations of the spins, should also be tuned by such external parameters, which is an important property for future magnonics. Here, we conduct resonant inelastic x‐ray scattering (RIXS) at the Fe L-edge to investigate the spin dynamics of BiFeO3 thin films under various strains. We found that the magnon bandwidth decreases linearly as compressive strain increases. However, our investigation of spin-wave dispersions also captured a strain evolution of the spin-waves, which cannot be explained by a simple scaling of exchange interaction. These findings can bring us a new opportunity for controlling magnons. |
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