Ivan V. Lisenkov

• PhD
• PostDoc Position at Northeastern University

The development of compact and tunable room temperature sources of coherent THz-frequency signals would open a way for numerous new applications. The existing approaches to THz-frequency generation based on superconductor Josephson junctions (JJ), free electron lasers, and quantum cascades require cryogenic temperatures or/and complex setups, preve...

Approximate electrodynamic boundary conditions are derived for an array of dipolarly coupled magnetic elements. It is assumed that the elements' thickness is small compared to the wavelength of an electromagnetic wave in a free space. The boundary conditions relate electric and magnetic fields existing at the top and bottom sides of the array...

It is demonstrated theoretically that a thin layer of an anisotropic antiferromagnetic (AFM) insulator can effectively conduct spin current by excitation of a pair of evanescent AFM spin wave modes. The spin current flowing through the AFM is not conserved due to interaction between the excited AFM modes and the AFM lattice, and, depending on the e...

A design of a magnonic phase shifter operating without an external bias magnetic field is proposed. The phase shifter uses a localized collective spin wave mode propagating along a domain wall "waveguide" in a dipolarly-coupled magnetic dot array existing in a chessboard antiferromagnetic (CAFM) ground state. It is demonstrated numerically that rem...

A general theory of collective spin-wave edge modes in semi-infinite and finite periodic arrays of magnetic nanodots having uniform dynamic magnetization (macrospin approximation) is developed. The theory is formulated using a formalism of multivectors of magnetization dynamics, which allows one to study edge modes in arrays having arbitrarily comp...

Nonreciprocity, the defining characteristic of isolators, circulators, and a wealth of other applications in radio/microwave communications technologies, is generally difficult to achieve as most physical systems incorporate symmetries that prevent the effect. In particular, acoustic waves are an important medium for information transport, but they...

An analog microwave signal correlator, based on parametric pumping of a spin wave by an rf magnetic field, is demonstrated. The binary codes to be correlated modulate the two microwave signals input to the device to, respectively, excite the spin wave and rf field at twice the carrier frequency of the spin wave. The magnetic field parametrically pu...

It is shown theoretically that in a layered heterostructure comprising piezoelectric, dielectric antiferromagnetic crystal, and heavy metal (PZ/AFM/HM), it is possible to control the anisotropy of the AFM layer by applying a dc voltage across the PZ layer. In particular, we show that by varying the dc voltage across the heterostructure and/or the d...

Nonreciprocity, the defining characteristic of isolators, circulators and a wealth of other applications in radio/microwave communications technologies, is in general difficult to achieve as most physical systems incorporate symmetries that prevent the effect. In particular, acoustic waves are an important medium for information transport, but they...

A theory of magnetization dynamics in ferrimagnetic materials with antiparallel aligned spin sublattices under the action of spin-transfer torques (STTs) is developed. In contrast with antiferromagnets, the magnetic sublattices in ferrimagnets are formed by different magnetic ions, which results in a symmetry breaking in the dynamic equations for N...

A theory of parametric interaction between spin waves localized in a waveguide and traveling elastic waves is developed for ferromagnetic thin films. The presented theoretical formalism takes into account an arbitrary spatial distribution of the displacement field in the acoustic waves and an arbitrary magnetization in spin waves. Using the theory,...

A theory of magnetization dynamics in ferrimagnetic materials with antiparallel aligned spin sub-lattices under action of spin-transfer torques (STT) is developed. We consider magnetization dynamics in GdFeCo layers in two cases of magnetic anisotropy: easy plane and easy axis. We demonstrate that, (i) for the easy plane anisotropy the precession o...

A magneto-elastic coupling provides a way to control the magnetic degree of order by physical deformations of the sample. Dynamics of coupled magnetic and elastic systems has been successfully studied theoretically in bulk systems by analyzing the magneto-elastic Hamiltonian and deriving equations of motion of magneto-elastic oscillations. This app...

We demonstrate analytically and numerically, that a thin film of an antiferromagnetic (AFM) material, having biaxial magnetic anisotropy and being driven by an external spin-transfer torque signal, can be used for the generation of ultra-short "Dirac-delta-like" spikes. The duration of the generated spikes is several picoseconds for typical AFM mat...

It has been shown previously that spin-Hall oscillators based on current-driven bi-layered film structures containing an antiferromagnet (AFM) and a normal metal can generate ultra-short (∼2 ps) “spike-like” pulses in response to an external current stimulus of a sufficient amplitude, thus operating as ultra-fast artificial “neurons.” Here, we repo...

Surface acoustic waves (SAWs) propagating in a piezoelectric substrate covered with a thin ferromagnetic–heavy-metal bilayer are found to exhibit a substantial degree of nonreciprocity, i.e., the frequencies of these waves are nondegenerate with respect to the inversion of the SAW propagation direction. The simultaneous action of the magnetoelastic...

We demonstrate analytically and numerically, that a thin film of an antiferromagnetic (AFM) material, having biaxial magnetic anisotropy and being driven by an external spin-transfer torque signal, can be used for the generation of ultra-short "Dirac-delta-like" spikes. The duration of the generated spikes is several picoseconds for typical AFM mat...

The Bose-Einstein condensate of magnons (mBEC) that is formed at room temperature in parametrically pumped magnetic films is doubly degenerate: it is formed simultaneously in two spectral minima corresponding to the lowest-energy magnons propagating in opposite directions along the in-plane bias magnetic field. In this work the interactions of magn...

A spin-torque nano-oscillator (STNO) driven by a ramped bias current can perform spectrum analysis quickly over a wide frequency bandwidth. The STNO spectrum analyzer operates by injection locking to external microwave signals and produces an output DC voltage $V_{\rm dc}$ that temporally encodes the input spectrum. We found, via numerical analysis...

The development of compact and tunable room temperature sources of coherent THz-frequency signals would open a way for numerous new applications. The existing approaches to THz-frequency generation based on superconductor Josephson junctions (JJ), free electron lasers, and quantum cascades require cryogenic temperatures or/and complex setups, preve...

A signal phase instead of a signal amplitude will be used to carry information in emerging novel computational and signal processing systems based on magnonic logic [1] and employing neuromorphic [2] and holographic computing [3]. In this study, we present an element of the phase-based signal processing system that acts as a GHz-frequency spin wave...

A lecture aimed on undergraduate physics majors on research carried out at the Department of Physics OU.

A design of a magnonic phase shifter operating without an external bias magnetic field is proposed. The phase shifter uses a localized collective spin wave mode propagating along a domain wall "waveguide" in a dipolarly-coupled magnetic dot array existing in a chessboard antiferromagnetic (CAFM) ground state. It is demonstrated numerically that rem...

A theoretical formalism for the description of the interaction of microwave photons with a thin (compared to the photon wavelength) magnetic metasurface comprised of dipolarly interacting nano-scale magnetic elements is developed. A scattering matrix describing the processes of photon transmission and reflection at the metasurface boundary is deriv...

A theoretical formalism for the description of the interaction of microwave photons with a thin (compared to the photon wavelength) magnetic metasurface comprised of dipolarly interacting nano-scale magnetic elements is developed. A scattering matrix describing the processes of photon transmission and reflection at the metasurface boundary is deriv...

Recent results in the topical and rapidly developing branch of spintronics and magnetoelectronics called magnonics are presented in this paper. The paper describes measurement techniques and theoretical approaches used to explore physical processes associated with the spin-wave propagation in complex nano- and micro-dimensional magnetic structures....

The existing spintronic devices typically use spin-polarized electron currents in metals to transfer spin angular momentum. Thus, in metallic systems the spin transfer requires also a transfer of charge, which limits the applicability of these systems due to the ohmic losses. Recently, a concept of a 'pure spin current' has been introduced in which...

The future progress of microwave technology is impossible without the development of novel man-made materials having designed-to-order physical properties. A good example of such man-made novel magnetic metamaterials are the arrays of dipolary coupled magnetic elements having crystal-lographic or/and shape anisotropy that allows them to function wi...

It is predicted that in 2D magnonic crystals the edge rotational magnons of forward vol-ume magnetostatic spin waves can exist. Under certain conditions locally bounded magnons may ap-pear within the crystal consisting of the ferromagnetic matrix and periodically inserted magnetic/non-magnetic inclusions. It is also shown that interplay of differen...

Arrays of magnetic nanopillars are promising components for future microwave spin wave devices operating without external bias magnetic field [1]. In our previous work have shown that edge modes exists in ferromagnetically ordered semi-infinite arrays of magnetic nanopillars, mainly supported by inhomogeneity of an internal magnetic field [2]. Now...

The frequency spectrum of spin-wave edge modes localized near the boundaries of a finite array of dipolarly coupled magnetic nanopillars is calculated theoretically. Two mechanisms of edge mode formation are revealed: inhomogeneity of the internal static magnetic field existing near the array boundaries and time-reversal symmetry breaking of the di...

It is predicted that in 2D magnonic crystals the edge rotational magnons of forward volume magnetostatic spin waves can exist. Under certain conditions, locally bounded magnons may appear within the crystal consisting of the ferromagnetic matrix and periodically inserted magnetic/non-magnetic inclusions. It is also shown that interplay of different...

The nonreciprocal properties of spin waves in metallized one-dimensional bi-component magnonic crystal composed of two materials with different magnetizations are investigated numerically. Nonreciprocity leads to the appearance of indirect magnonic band gaps for magnonic crystals with both low and high magnetization contrast. Specific features of t...

Motivation/background The effect of giant magnetostriction opens possibility to control stiffness of materials by means of magnetic fields. Despite of called 'giant', the changes of stiffness in absolute values, which can be obtained with reasonable values of magnetic fields are generally very small. In our work we show both theoretically and expe...

Acoustic wave propagation in a composite of water with embedded double-layered silicone resin/silver rods is considered. Approximate values of effective dynamical constitutive parameters are obtained. Frequency ranges of simultaneous negative constitutive parameters are found. Localized surface states on the interface between metamaterial and “norm...

The Doppler effect in doubly double negative acoustic media is theoretically investigated. The radiation spectra of a source moving relative to a medium are calculated with the help of the method of the Green’s functions. It is shown that several Doppler modes can be generated by a monochromatic source owing to the strong dependence of the wave num...

Acoustic Doppler effect in double negative acoustic resonance metamaterials is theoretically investi- gated. The radiation spectra of the moving, with respect to the medium, source of acoustic oscillations are calculated using Green functions method. It is shown that due to strong wave-number frequency dependence generation of a number of Doppler m...

Propagating of the acoustic wave in quasi-isotropic metamaterial is considered. The composite is consisted of an isotropic background material and embedded resonators in it. The frequency of the wave is taken that the wavelength is much longer that size of inclusions and distance between them. Dispersion of effective stiffness and density is calcul...

Elastic wave propagation along the structure of hollow cylinders in a linear isotropic medium is investigated. The multipole method for modeling elastic waves propagation in such structures is formulated and implemented. Using the multipole method, dispersion dependencies of the structures (microstructured fibers) containing 3, 6, and 7 hollow cyli...

Two ways of modeling of elastic wave propagation in microstructured acoustic fiber are considered. First one is the calculation of band gap parameters by FEM for phononic crystal forming cross section of fiber. Second one is immediate calculation of dispersion characteristics of elastic fiber containing hole cylindric chanels. For fiber made of fus...

The review of current state of the art of bulk and surface linear and nonlinear acoustic wave propagation in phononic crystals (PhC) is given. First, theoretical analysis of bulk acoustic waves propagation in 2D phononic crystals composed of elastic medium with periodic systems of air holes with different symmetry is considered. The properties of h...

Propagation of elastic waves in a system of cylindrical channels embedded in a homogeneous isotropic elastic medium (a phononic crystal) is investigated. A multipole method is proposed for simulation of wave propagation in such structures. The dispersion characteristics of wave propagation in systems consisting of three, six, and seven cylindrical...