Article
Chemistry, Multidisciplinary
Nilamani Behera, Avinash Kumar Chaurasiya, Victor H. Gonzalez, Artem Litvinenko, Lakhan Bainsla, Akash Kumar, Roman Khymyn, Ahmad A. Awad, Himanshu Fulara, Johan Akerman
Summary: This study identifies the current shunting issue through the Si substrate as a major problem in scaling down nano-constriction based spin Hall nano-oscillators (SHNOs). By using an ultra-thin Al2O3 seed layer and SiN-coated p-Si substrates, the researchers successfully mitigate this problem and achieve SHNOs with a width as small as 10 nm and threshold currents below 30 muA. The combination of electrical insulation and high thermal conductivity of the Al2O3 seed layer also makes it suitable for large SHNO arrays.
ADVANCED MATERIALS
(2023)
Article
Physics, Applied
Lina Chen, Zhenyu Gao, Kaiyuan Zhou, Y. W. Du, R. H. Liu
Summary: Pure spin currents have been shown to excite a single coherent spinwave mode in a nonlocal spin-injection spin-valve device. The observed spin-wave mode is a linear propagating mode with a frequency higher than the ferromagnetic resonance frequency. Micromagnetic simulations based on the device geometry reproduce the oscillation characteristics and show collimated and bidirectional propagation paths for the spin-wave mode.
PHYSICAL REVIEW APPLIED
(2021)
Article
Chemistry, Multidisciplinary
Akash Kumar, Himanshu Fulara, Roman Khymyn, Artem Litvinenko, Mohammad Zahedinejad, Mona Rajabali, Xiaotian Zhao, Nilamani Behera, Afshin Houshang, Ahmad A. Awad, Johan akerman
Summary: Mutual synchronization of serially connected spintronic nano-oscillators can increase their coherence and peak power. Increasing the number of synchronized oscillators in chains is significant for improving signal quality and developing oscillator-based unconventional computing.
Article
Chemistry, Multidisciplinary
Chi Zhang, Inhee Lee, Yong Pu, Sergei A. Manuilov, Denis V. Pelekhov, P. Chris Hammel
Summary: The research team demonstrated a high-quality spin-orbit torque nano-oscillator consisting of spin wave modes confined by the strongly inhomogeneous dipole field of a nearby micromagnet. This approach allows for variable spatial confinement and systematic tuning of magnon spectrum and spectral separations to study the impact of multimode interactions on auto-oscillations. The dipole-field-localized spin wave modes exhibit favorable characteristic properties as auto-oscillators, with narrow line width and large amplitude, persisting up to room temperature.
Article
Multidisciplinary Sciences
Kyuhwe Kang, Hiroki Omura, Daniel Yesudas, OukJae Lee, Kyung-Jin Lee, Hyun-Woo Lee, Tomoyasu Taniyama, Gyung-Min Choi
Summary: In this study, the spin current in a FeRh/Cu heterostructure during the ultrafast magnetization process is directly measured, revealing a significant correlation between the spin current and the magnetization dynamics. This suggests an angular momentum transfer mechanism from electrons to magnons, involving spatial transport and dissipation of angular momentum. This finding contributes to a better understanding of laser-induced ultrafast magnetization processes.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Benjamin Wolba, Olena Gomonay, Volodymyr P. Kravchuk
Summary: Theoretical description of a terahertz nano-oscillator based on an anisotropic antiferromagnetic dynamical element driven by spin torque reveals chaotic behavior with particularly low threshold current near the spin-flop transition. Prior to the appearance of chaos, a regime of quasiperiodic dynamics on the surface of a two-frequency torus may occur.
Article
Engineering, Electrical & Electronic
Raghav Sharma, Naveen Sisodia, Johan Akerman, P. K. Muduli
Summary: The modulation bandwidth (f(BW)) is a critical figure-of-merit for wireless communication applications of spin torque nano-oscillators (STNOs) as it determines the maximum data rate. A single-shot time-resolved measurements of a magnetic tunnel junction based STNO demonstrated that f(BW) can be many times larger under strong modulation, indicating a potential for future wireless applications. This behavior was qualitatively reproduced in macrospin simulations, suggesting that f(BW) of STNOs may not be as limiting a factor for future wireless applications as previously believed.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Nanoscience & Nanotechnology
Jindi Feng, Kunpeng Li, Mingkun Zheng, Xiaojuan Yuan, Yong Liu, Zhihong Lu, Rui Xiong
Summary: This study investigates the dynamical behaviors of an all-permalloy structured spin-torque nano-oscillator (STNO) and finds that it can exhibit two stable precession modes of magnetization under varying applied DC current densities. The switching between the modes can be achieved through pulsed magnetic field, and the output power can be significantly enhanced by building an array of STNOs.
Article
Chemistry, Multidisciplinary
Sheng Jiang, Sunjae Chung, Quang Tuan Le, Ping Kwan Johnny Wong, Wen Zhang, Johan Akerman
Summary: Exchange-spring STNOs are demonstrated to generate high-frequency microwave emission at zero magnetic field and observe magnetic droplet solitons. This extends the design flexibility and functionality of current STNO technology for energy-efficient high-frequency spintronics and neuromorphic applications.
Article
Physics, Applied
Xiuping Zhou, Hanyu Ren, Congying Jiang, Fan Wang, Xinyan He, Zhenzhen Chen, Yang Qiu, Mingmin Zhu, Guoliang Yu, Haomiao Zhou
Summary: In this study, we demonstrate the controlled injection of domain walls (DWs) in a ferromagnetic nanostrip using spin-transfer torque (STT), enabled by modified perpendicular magnetic anisotropy (PMA) in Pt/Co. The presence of a 90-degree magnetized transition region is shown to be crucial for the injection process, with the generation frequency of DWs being reversibly controlled in the MHz to multi-GHz range. These findings highlight the feasibility of a highly tunable and direct-current-controlled transverse in-plane DW signal source, which has potential applications in compact and integrated DW circuits and oscillators.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Zhendong Chi, Guanxiong Qu, Yong-Chang Lau, Masashi Kawaguchi, Junji Fujimoto, Koki Takanashi, Masao Ogata, Masamitsu Hayashi
Summary: The spin Hall effect of a Dirac Hamiltonian system is studied using semiclassical analyses and the Kubo formula. It is found that the spin Hall conductivity is dependent on the definition of spin current, and when defined as the flow of spin magnetic moment, it has non-zero off-diagonal components. The analytical formula derived in this study is able to quantitatively explain the experimental results, indicating that the giant spin magnetic moment with an effective g factor approaching 100 is responsible for the spin Hall effect in Bi.
Article
Materials Science, Multidisciplinary
Mohammad Haidar
Summary: This study investigates the excitation of short-wavelength spin waves in nanowire-based spin-Hall nano-oscillators. The researchers found that shorter wavelengths are excited in narrower nanowire widths at higher magnetic fields and higher currents. By reducing the nanowire width, ultrashort spin waves with wavelengths as short as 80 nm can be generated, which may have significant implications for the scalability of magnonic devices.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Multidisciplinary Sciences
Jong-Guk Choi, Jaehyeon Park, Min-Gu Kang, Doyoon Kim, Jae-Sung Rieh, Kyung-Jin Lee, Kab-Jin Kim, Byong-Guk Park
Summary: This study shows that the frequency of SHNOs can be controlled up to 2.1 GHz by an electric field, enabling large frequency tuning. The voltage-controlled frequency tuning of SHNOs facilitates the development of energy-efficient neuromorphic devices. Additionally, repetitive voltage pulses can be used to cumulatively control the frequency, mimicking the functions of biological synapses.
NATURE COMMUNICATIONS
(2022)
Article
Materials Science, Multidisciplinary
Danijela Markovic, Matthew W. Daniels, Pankaj Sethi, Andrew D. Kent, Mark D. Stiles, Julie Grollier
Summary: Analytically showing that easy-plane spin Hall nano-oscillators excited by a spin current polarized perpendicularly to the easy plane have phase dynamics similar to Josephson junctions, suitable for neuromorphic computing. Utilizing a specific nanoconstriction geometry, the easy-plane spiking dynamics are maintained in an experimentally feasible architecture. Two elementary neural network blocks essential for neuromorphic computing are simulated, demonstrating the summing and injection of output spikes energies and the multiplication of outputs by synaptic weights.
Article
Physics, Multidisciplinary
Biao Jiang, Wen-Jun Zhang, Mehran Khan Alam, Shu-Yun Yu, Guang-Bing Han, Guo-Lei Liu, Shi-Shen Yan, Shi-Shou Kang
Summary: Micromagnetic simulations have revealed that the power spectra of nanowire-based spin Hall nano-oscillator (SHNO) devices can be synchronized by adjusting the current flowing in the heavy metal layer. The synchronized signals exhibit high power and narrow linewidth, making them suitable for potential applications. The characteristics of the synchronized spectra depend strongly on the number and length of nanowires. Additionally, introducing interfacial Dzyaloshinskii-Moriya interaction can lead to periodic modulation of the power spectra.
Article
Physics, Applied
A. S. Bogolubskiy, A. S. Klepikova, A. B. Rinkevich, V. N. Neverov, O. V. Nemytova, M. S. Koroleva, I. V. Piir, D. V. Perov
Summary: Ytterbium and holmium titanates have been synthesized and investigated for their dielectric and magnetic properties. The frequency dependences of permittivity at different temperatures, measured magnetization curves, and temperature dependences of magnetic susceptibility in various fields have been studied. Comparisons have been made between doped and undoped titanates, and analysis of magnetic dipole and exchange couplings in the titanates has been conducted based on temperature dependences of magnetic susceptibility.
LOW TEMPERATURE PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Anatoly B. Rinkevich, Yuri Ryabkov, Dmitry Perov, Olga Nemytova
Summary: The study investigated the microwave refraction coefficient and magnetic field dependence of a composite made of Fe-Si-Nb-Cu-B alloy flakes in an epoxy resin matrix, and found that the material behaves as a dielectric in the absence of magnetic field and near ferromagnetic resonance, the real and imaginary parts of the complex refraction coefficient are comparable to a conductive medium.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Olga V. Nemytova, Anatoly B. Rinkevich, Dmitry V. Perov
Summary: The frequency and magnetic field dependences of the dynamic AC susceptibility in nanocomposites based on opal matrixes with Co and Pd particles were studied. The differential DC susceptibility was found to be similar to the dynamic AC susceptibility measured at 1 Hz, but different from the susceptibility measured at higher frequencies. Three relaxation times were calculated using the Cole-Cole formula for samples with hexagonal Co and metallic Pd. The field dependences of the differential DC susceptibility were different from the field dependences of the dynamic AC susceptibility measured at frequencies of 10, 100 Hz and 1 kHz.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Yu. V. Korkh, A. B. Rinkevich, A. S. Klepikova, E. A. Tolmacheva, E. A. Pankrushina
Summary: The study compares the surface potential and local electrostatic properties of graphene films on different dielectric substrates, revealing that the type of substrate, number of layers, and defects will affect the surface potential distribution of graphene.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2022)
Article
Metallurgy & Metallurgical Engineering
D. Perov, A. B. Rinkevich
Summary: A method for calculating the microwave permeability of a magnetized composite with ellipsoidal particles is proposed. The orientation of the ellipsoid axes relative to the coordinate axes is taken into account. The study determines the dependence of the components of the permeability tensor and effective permeability on the magnetic field and frequency, and calculates the field dependence of the effective permeability for composites consisting of particles with different shapes.
PHYSICS OF METALS AND METALLOGRAPHY
(2022)
Article
Multidisciplinary Sciences
H. Merbouche, B. Divinskiy, K. O. Nikolaev, C. Kaspar, W. H. P. Pernice, D. Gouere, R. Lebrun, V Cros, J. Ben Youssef, P. Bortolotti, A. Anane, S. O. Demokritov, V. E. Demidov
Summary: This study demonstrates the complexity of nonlinear wave processes in microscopic magnetic structures and emphasizes the importance of understanding them for technical applications of spin waves in integrated devices.
SCIENTIFIC REPORTS
(2022)
Article
Physics, Applied
S. R. Lake, B. Divinskiy, G. Schmidt, S. O. Demokritov, V. E. Demidov
Summary: Phase-resolved imaging is used to study the nonlinear modification of wavelength in spin wave propagation. It is found that using moderate microwave power can generate spin waves with large amplitudes, and large precession angles lead to strong spatial dependence of wavelength. These findings are important for optimizing nonlinear integrated spin-wave signal-processing devices.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Applied
S. R. Lake, B. Divinskiy, G. Schmidt, S. O. Demokritov, V. E. Demidov
Summary: Magnonics utilizes both the amplitude and phase of spin waves, with tunable phase shifters being crucial elements for magnonic circuits. This study demonstrates that intrinsic magnetic nonlinearities enable efficient microscopic tunable phase shifters controlled by wave intensity. The phase shift tunability can reach over 360 degrees with a few milliwatts of microwave power, showing promise for integrated nano-magnonics in computing beyond Moore's Law.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Anatoly B. Rinkevich, Dmitry V. Perov, Evgeny A. Kuznetsov, Olga V. Nemytova, Mikhail A. Milyaev, Vladimir V. Ustinov
Summary: The microwave giant magnetoresistance (mu GMR) effect in (CoFe/Cu)/glass structures was investigated. Measurements were conducted on a metal superlattice and a dielectric substrate, showing a sharp increase in mu GMR for a reflected wave when the substrate thickness was three-quarters of a wavelength. This effect is associated with a significant decrease in reflection coefficient and the large magnitude of magnetoresistance effect in the superlattices (CoFe/Cu).
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Physical
Anatoly B. Rinkevich, Dmitry Perov, Elena A. Tolmacheva, Evgeny A. Kuznetsov, Olga Nemytova, Mikhail A. Uimin
Summary: The magnetic and microwave properties of nanocomposites containing iron particles encapsulated in a carbon shell (Fe@C) and carbon nanotubes (CNT) have been experimentally studied. The composites were found to contain a ferromagnetic component, and the presence of ferromagnetic ordering was confirmed by measuring the transmission and reflection coefficients of microwaves. The measurement results show the observations of ferromagnetic resonance and signs of ferromagnetic antiresonance.
Article
Chemistry, Physical
Anatoly B. Rinkevich, Dmitry Perov, Evgeny A. Kuznetsov, Yulia Korkh, Anna S. Klepikova, Yury Ryabkov
Summary: This study investigates the absorption of centimeter and millimeter waves in composites with Finemet alloy particles and carbon nanotubes. It proposes a method to calculate the effective dynamic magnetic permeability of a composite containing randomly distributed ferromagnetic particles and aligned particles. The study confirms the existence of ferromagnetic resonance and antiresonance in the composites through theoretical calculations.
Article
Materials Science, Composites
Anatoly B. Rinkevich, Olga V. Nemytova, Dmitry V. Perov
Summary: The DC and AC magnetic susceptibilities of a nanocomposite based on opal matrix with pyrochlore-structured ytterbium titanate particles up to 60 nm in size are studied, with magnetic fields up to 30 kOe. The temperature dependence of the nanocomposite Yb2Ti2O7 deviates significantly from the Curie-Weiss law. The frequency dependence of the AC susceptibility reveals the presence of two relaxation times, and the field dependence of the AC susceptibility is described by the modified Cole-Cole formula. The characteristic fields of the magnetic field dependence of the real part of the susceptibility increase with increasing temperatures.
JOURNAL OF COMPOSITES SCIENCE
(2023)
Article
Mechanics
V. V. Ustinov, A. B. Rinkevich, M. A. Milyaev, E. A. Kuznetsov, D. V. Perov
Summary: The giant microwave magnetoresistance effect for wave reflection in the superlattice (CoFe)/Cu-substrate system is investigated. The dependence of reflection coefficient on the strength of the magnetic field is measured within the frequency range of 26-38 GHz.
Article
Nanoscience & Nanotechnology
Hugo Merbouche, Martin Collet, Michael Evelt, Vladislav E. Demidov, Jose Luis Prieto, Manuel Munoz, Jamal Ben Youssef, Gregoire de Loubens, Olivier Klein, Stephane Xavier, Olivier D'Allivy Kelly, Paolo Bortolotti, Vincent Cros, Abdelmadjid Anane, Sergej O. Demokritov
Summary: Magnonics rely on the wave nature of magnetic excitations to process information at frequencies between a few GHz to tens of GHz, suitable for operation in radio-frequency bands for 4G and 5G telecommunications. A micron-scale magnonic crystal was used to demonstrate radio-frequency signal filtering with a frequency selectivity of 20 MHz at an operating frequency of 4.9 GHz, providing insight into the physics of SW propagation in periodically modulated nanoscale structures.
ACS APPLIED NANO MATERIALS
(2021)
