A5055197582- Magnetic properties of thin films
- Physics of Superconductivity and Magnetism
- Quantum and electron transport phenomena
- Magnetic Properties and Applications
- Theoretical and Computational Physics
- ZnO doping and properties
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Anodic Oxide Films and Nanostructures
- Magneto-Optical Properties and Applications
- Force Microscopy Techniques and Applications
- Characterization and Applications of Magnetic Nanoparticles
- Iron-based superconductors research
- Advanced Electrical Measurement Techniques
- Atomic and Subatomic Physics Research
- Nonlinear Dynamics and Pattern Formation
- Acoustic Wave Resonator Technologies
- Plant and Fungal Species Descriptions
- Liquid Crystal Research Advancements
- Nanofabrication and Lithography Techniques
- Smart Materials for Construction
- Ferroelectric and Negative Capacitance Devices
- Advanced Memory and Neural Computing
- Nanopore and Nanochannel Transport Studies
- Advancements in Semiconductor Devices and Circuit Design
CEA Grenoble
2015-2025
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2015-2025
Spintronique et Technologie des Composants
2015-2025
Centre National de la Recherche Scientifique
2012-2024
Institut polytechnique de Grenoble
2009-2024
Université Grenoble Alpes
2013-2024
Institut Nanosciences et Cryogénie
2008-2023
Université Joseph Fourier
2008-2015
Oakland University
2011
CEA LETI
2009-2011
While the usual approach to tailor behavior of condensed matter and nanosized systems is choice material or finite-size interfacial effects, topology alone may be key. In context motion magnetic domain walls (DWs), known suffer from dynamic instabilities with low mobilities, we report unprecedented velocities $>600\text{ }\text{ }\mathrm{m}/\mathrm{s}$ for DWs driven by spin-transfer torques in cylindrical nanowires made a standard ferromagnetic material. The reason robust stabilization...
For the ``perpendicular polarizer-planar free layer'' spin torque oscillator a complete current-field state diagram in macrospin description is presented. This quite different from one of more commonly known ``planar oscillators. In particular, various regions bistability between two static states or and dynamic are evidenced plane. The boundaries regions, where become unstable, were deduced using generalized ferromagnetic resonance formalism that requires only knowledge second derivatives...
The microwave emission linewidth of spin transfer torque nano-oscillators is closely related to their phase and amplitude noise that can be extracted from the magnetoresistive voltage signal V(t) using single shot time domain techniques. Here we report on studies for MgO based magnetic tunnel junction oscillators. analysis power spectral densities allows one separate linear nonlinear contributions noise, contribution being due coupling between amplitude. strength as well relaxation rate...
Topologically protected magnetic states in condensed matter physics, particularly antiferromagnetic (AFM) skyrmions (Sks) and bimerons (Bms), offer promising prospects for terahertz dynamics sustained current-induced motion, thanks to their compensating multiple sub-lattice structure. However, nucleating AFM Sks Bms is challenging due the lack of net magnetization. Previous attempts imprint pre-defined a ferromagnet (FM) transfer them an using interfacial exchange bias FM/AFM...
Injection locking of a spin transfer nano-oscillator, based on an in-plane magnetized magnetic tunnel junction and generating the frequency f0, to external signal varying fe is studied experimentally with macrospin simulations. It shown, that if driving has form microwave current, effect well-pronounced near fe≅2f0, but almost completely absent fe≅f0, confirming predictions analytical theory. also shown noise plays important role in process, causing linewidth locked oscillation substantially...
We report on experimental studies about superconducting coupling through a thin ${\mathrm{Ni}}_{76}{\mathrm{Al}}_{24}$ film. A patterning process has been developed, which allows in combination with the wedge shaped deposition technique situ of 20 single $\mathrm{Nb}∕\mathrm{Al}∕{\mathrm{Al}}_{2}{\mathrm{O}}_{3}∕{\mathrm{Ni}}_{3}\mathrm{Al}∕\mathrm{Nb}$ multilayers, each its own well-defined ${\mathrm{Ni}}_{3}\mathrm{Al}$ thickness. Every multilayer consists 10 different sized Josephson...
Spin polarized current induced self oscillations have been investigated in both the free layer and synthetic antiferromagnetic (SAF) pinned of spin valve nanopillars. Compared with excitations, acoustic type SAF excitations are characterized by high emitted power much narrower linewidth. Furthermore, contrast to in-plane precession mode exhibits an unexpected crossover from redshift (df/dI<0) blueshift (df/dI>0) frequency f versus I as magnetic field is increased. From...
The influence of dynamic interactions on the spin-polarized current-induced steady state oscillations has been studied numerically for a spin torque oscillator that is composed free layer and synthetic antiferromagnetic (SAF) pinned layer. Two types dynamical have considered. first exchange interaction between two layers constitute SAF second mutual Taking these into account, Landau-Lifshitz-Gilbert equation including transfer solved simultaneously all three in macrospin approach. Besides...
Micromagnetic simulations are presented to describe the magnetization dynamics of a spin torque oscillator that combines an out-of-plane magnetized polarizer with in-plane free layer. This configuration provides possibility excite large-angle steady-state oscillations layer above threshold current and in zero external field. While macrospin approximation, frequency these increases monotonously increasing density, full micromagnetic reveal two branches for vs dependency: first branch at lower...
Abstract Domain wall propagation in modulated-diameter cylindrical nanowires is a key phenomenon to be studied with view designing three-dimensional magnetic memory devices. This paper presents theoretical study of transverse domain behavior under the influence field within nanowire diameter modulations. In particular, pinning close modulation was quantified, both numerically, using finite element micromagnetic simulations, and analytically. Qualitative analytical model for gently sloping...
We demonstrate by macrospin simulations that in a spin-torque nano-oscillator having synthetic antiferromagnet fixed layer, the non-conservative dynamic coupling between free and layers caused effect leads to substantial reduction of linewidth current-induced spin wave mode, involving oscillations all three magnetic layers. By analysing phase amplitude noise extracted from simulated signal, we prove obtained is related dimensionless non-linear amplitude-phase parameter ν.
The charge and spin diffusion equations, taking into account spin-flip spin-transfer torque, were numerically solved using a finite element method in complex noncollinear geometry with strongly inhomogeneous current flow. As an illustration, spin-dependent transport through nonmagnetic nanoconstriction, separating two magnetic layers was investigated. Unexpected results such as vortices of spin-currents the vicinity nanoconstriction obtained. angular variations magnetoresistance torque are...
The spin-torque-driven in-plane precession mode of synthetic antiferromagnets (SAFs) is characterized by a frequency current dependence that changes its slope from negative redshift to positive blueshift upon increasing the applied magnetic field. Here, we show transition due additional torques arising dynamic interlayer exchange coupling SAF. These depend on amplitude with and We present an analysis corresponding energy surface able predict such behavior for any excitation coupled two-layer system.
In an isochronous auto-oscillator, where the auto-oscillation frequency $f$ does not depend on oscillation amplitude, linewidth of $n$th harmonic is ${n}^{2}$ times larger than main mode. Here we present a theoretical description that predicts increase in higher harmonics with number $n$ substantially slower case nonisoschronous oscillator, depends strongly amplitude. Using spin-torque nano-oscillators as example nonisochronous this confirmed numerically and experimentally. The presented...
Three-dimensional magnetic memory design based on circular-cross section nanowires with modulated diameter is the emerging field of spintronics. The consequences mutual interaction between electron spins and local moments in such non-trivial geometries are still open to debate. This paper describes theoretical study domain wall dynamics within wires subjected spin polarized current. We used our home-made finite element software characterize variety dynamical regimes observed for different...
We study the influence of configuration majority and minority spin subbands electron spectra on properties atomic-scaled superconductor-ferromagnet S-F-S F-S-F hybrid structures. At low temperatures, S/F/S junction is either a 0 or depending energy shift between S F materials anisotropy Fermi surfaces. found that switch effect in F/S/F system can be reversed if metal hole-like type.
A comprehensive numerical study of the spin toque driven dynamic states is presented for a synthetic ferrimagnet. For this, Landau-Lifshitz-Gilbert equation has been solved simultaneously two coupled layers ferrimagnet in macrospin approach including transfer torque term from an external polarizer one them. It shown that large variety modes (in-plane precession (IPP) and out-of-plane precession) can be established, upon varying strength exchange bias field pins SyF as well...
The spin absorption process in a ferromagnetic material depends on the orientation relativelyto magnetization. Using ferromagnet to absorb pure current created within lateralspin-valve, we evidence and quantify sizeable dependence of inCo, CoFe NiFe. These experiments allow determining spin-mixing conductance, an elusivebut fundamental parameter spin-dependent transport. We show that obtained valuescannot be understood model considering only Larmor, transverse decoherence spindiffusion...
Two types of domain walls exist in magnetically soft cylindrical nanowires: the transverse-vortex wall (TVW) and Bloch-point (BPW). The latter is expected to prevent usual Walker breakdown thus enable high speed. We showed recently [M. Sch\"obitz et al., Phys. Rev. Lett. 123, 217201 (2019)] that previously overlooked Oersted field associated with an electric current a key experiments stabilize BPW reach speed above $600\phantom{\rule{0.28em}{0ex}}\mathrm{m}/\mathrm{s}$ spin transfer. Here,...
We report a theoretical overview of the magnetic domain wall behavior under an electric current in infinitely-long nanotubes with azimuthal magnetization, combining $1$D analytic model and micromagnetic simulations. highlight effects that, besides spin-transfer torques already largely understood flat strips, arise specifically tubular geometry: \OErsted field curvature-induced anisotropy resulting both from exchange material growth. Depending on geometry tube strength anisotropy, Bloch or...
In this paper, we use simulations to study current-induced domain wall dynamics by simultaneously resolving the spin transport and micromagnetic equations for a three-dimensional ferromagnetic strip. contrast local approaches, which neglect mutual interaction between spins magnetic moments, our approach recalculates distribution at each time step using generalized drift diffusion model, takes transverse absorption phenomenon into account. We quantified differences treatment based on...