Olivier Bultynck, Mauricio Manfrini, Adrien Vaysset, Johan Swerts, Christopher J. Wilson, Bart Sorée, Marc Heyns, D. Mocuta, Iuliana Radu, T. Devolder,
Spin-torque-operated magnetic tunnel junctions (MTJs) with perpendicular magnetic anisotropy are established charge-to-spin transducers. Their switching speed is still fundamentally limited by thermal activation, however, leading to slower switching in memory applications. In this study a canted magnetization state is engineered to overcome the incubation delay, for faster switching times. Comparison to perpendicular MTJs is performed, with direct time-resolved observation of switching dynamics in ...
Tópico(s): Quantum and electron transport phenomena
2018 - American Physical Society | Physical Review Applied
Eline Raymenants, Adrien Vaysset, Danny Wan, Mauricio Manfrini, Odysseas Zografos, Olivier Bultynck, Jonas Doevenspeck, Marc Heyns, Iuliana Radu, T. Devolder,
In the context of neuromorphic computation, spintronic memristors are investigated for their use as synaptic weights. In this paper, we propose and experimentally demonstrate a resistive synaptic device based on ten magnetic tunnel junctions (MTJs) connected in a serial configuration. Our device exhibits multiple resistance levels that support its use as a synaptic element. It allows for two operating knobs: external magnetic field and voltage pulses (Spin-Transfer Torque). Moreover, it can be operated ...
Tópico(s): Transition Metal Oxide Nanomaterials
2018 - American Institute of Physics | Journal of Applied Physics
Odysseas Zografos, Sourav Dutta, Mauricio Manfrini, Adrien Vaysset, Bart Sorée, Azad Naeemi, Prasanth Raghavan, Rudy Lauwereins, Iuliana Radu,
A spin wave majority fork-like structure with feature size of 40 nm, is presented and investigated, through micromagnetic simulations. The structure consists of three merging out-of-plane magnetization spin wave buses and four magneto-electric cells serving as three inputs and an output. The information of the logic signals is encoded in the phase of the transmitted spin waves and subsequently stored as direction of magnetization of the magneto-electric cells upon detection. The minimum dimensions ...
Tópico(s): Advancements in Semiconductor Devices and Circuit Design
2017 - American Institute of Physics | AIP Advances
Odysseas Zografos, Mauricio Manfrini, Adrien Vaysset, Bart Sorée, Florin Ciubotaru, Christoph Adelmann, Rudy Lauwereins, Praveen Raghavan, Iuliana Radu,
Direct exchange interaction allows spins to be magnetically ordered. Additionally, it can be an efficient manipulation pathway for low-powered spintronic logic devices. We present a novel logic scheme driven by exchange between two distinct regions in a composite magnetic layer containing a bistable canted magnetization configuration. By applying a magnetic field pulse to the input region, the magnetization state is propagated to the output via spin-to-spin interaction in which the output state ...
Tópico(s): Advancements in Semiconductor Devices and Circuit Design
2017 - Nature Portfolio | Scientific Reports
Adrien Vaysset, Mauricio Manfrini, Dmitri E. Nikonov, Sasikanth Manipatruni, Ian A. Young, Geoffrey Pourtois, Iuliana Radu, Aaron Thean,
The functionality of a cross-shaped Spin Torque Majority Gate is explored by means of micromagnetic simulations. The different input combinations are simulated varying material parameters, current density and size. The main failure mode is identified: above a critical size, a domain wall can be pinned at the center of the cross, preventing further propagation of the information. By simulating several phase diagrams, the key parameters are obtained and the operating condition is deduced. A simple ...
Tópico(s): Semiconductor materials and devices
2016 - American Institute of Physics | AIP Advances
Florin Ciubotaru, T. Devolder, Mauricio Manfrini, Christoph Adelmann, Iuliana Radu,
We develop an all electrical experiment to perform the broadband phase-resolved spectroscopy of propagating spin waves in micrometer sized thin magnetic stripes. The magnetostatic surface spin waves are excited and detected by scaled down to 125 nm wide inductive antennas, which award ultra broadband wavevector capability. The wavevector selection can be done by applying an excitation frequency above the ferromagnetic resonance. Wavevector demultiplexing is done at the spin wave detector thanks ...
Tópico(s): Advanced Memory and Neural Computing
2016 - American Institute of Physics | Applied Physics Letters
A. van den Brink, Stefan Cosemans, S. Cornelissen, Mauricio Manfrini, Adrien Vaysset, W. Van Roy, Tai Min, H. J. M. Swagten, B. Koopmans,
We propose a write scheme for perpendicular spin-transfer torque magnetoresistive random-access memory that significantly reduces the required tunnel current density and write energy. A sub-nanosecond in-plane polarized spin current pulse is generated using the spin-Hall effect, disturbing the stable magnetic state. Subsequent switching using out-of-plane polarized spin current becomes highly efficient. Through evaluation of the Landau-Lifshitz-Gilbert equation, we quantitatively assess the viability ...
Tópico(s): Advanced Memory and Neural Computing
2014 - American Institute of Physics | Applied Physics Letters
S. Petit, R. M. Otxoa, Mauricio Manfrini,
We compute the electrical current flow and associated Oersted fields in magnetic nanocontact (NC) systems with finite-element simulations. Underneath the nanocontact, the current distribution is found to be mainly perpendicular to the film plane, while the flow is essentially in the film plane outside the nanocontact region. For circular nanocontacts, we provide criteria for which the cylindrical approximation remains valid for electrical flow in asymmetric rectangular devices. The nature of the ...
Tópico(s): Quantum and electron transport phenomena
2012 - American Institute of Physics | Applied Physics Letters
S. Petit, R. M. Otxoa, Mauricio Manfrini, W. Van Roy, Liesbet Lagae, Joo-Von Kim, T. Devolder,
We have determined the temperature profile in magnetic nanocontacts under applied current densities typical of spin-torque oscillators (∼10(8) A/cm2). The study combines experimental measurements of the electrical and magnetic properties of the nanocontacts and full three-dimensional simulations of the heat and current flow in these systems. It is found that the quadratic current-induced increase of the resistance due to Joule heating is independent of the applied temperature from 6 to 300 K. In terms ...
Tópico(s): Physics of Superconductivity and Magnetism
2012 - American Physical Society | Physical Review Letters
Mauricio Manfrini, T. Devolder, Joo-Von Kim, P. Crozat, C. Chappert, W. Van Roy, Liesbet Lagae,
Vortex-based spin-torque oscillators can be made from extended spin valves connected to an electrical nanocontact. We study the implementation of frequency shift keying modulation in these oscillators. Upon a square modulation of the current in the 10 MHz range, the vortex frequency follows the current command, with easy identification of the two swapping frequencies in the spectral measurements. The frequency distribution of the output power can be accounted for by convolution transformations of ...
Tópico(s): Physics of Superconductivity and Magnetism
2011 - American Institute of Physics | Journal of Applied Physics
T. Devolder, Joo-Von Kim, Mauricio Manfrini, W. Van Roy, Liesbet Lagae, C. Chappert,
We present an experimental study of the nucleation rate associated with current-driven vortex oscillations in magnetic nanocontacts. We find that the nucleation and subsequent steady-state oscillation of a vortex can be initiated using current pulses as short as a few nanoseconds, yielding instant on oscillator capability. The nucleation rate is governed by an Arrhenius law, with an exponential dependence on the applied current magnitude. The mechanism for the vortex nucleation is discussed and ...
Tópico(s): Physics of Superconductivity and Magnetism
2010 - American Institute of Physics | Applied Physics Letters
T. Devolder, Joo-Von Kim, P. Crozat, C. Chappert, Mauricio Manfrini, M. van Kampen, W. Van Roy, Liesbet Lagae, G. Hrkac, T. Schrefl,
We study vortex spin torque oscillators based on magnetic point contacts that operate in zero applied magnetic field. Static and dynamic vortex modes are shown to exist and have distinct electrical signatures. For the oscillatory mode, a spectrally pure slightly asymmetric voltage waveform is observed. It is subject to phase noise as sole fluctuations. The waveforms observed indicate that the vortex orbits outside the point contact region, with a pinned layer magnetization that is static but spatially ...
Tópico(s): Physics of Superconductivity and Magnetism
2009 - American Institute of Physics | Applied Physics Letters
Mauricio Manfrini, T. Devolder, Joo-Von Kim, P. Crozat, N. Zerounian, C. Chappert, W. Van Roy, Liesbet Lagae, G. Hrkac, T. Schrefl,
We study the agility of current-tunable oscillators based on a magnetic vortex orbiting around a point contact in spin-valves. Theory predicts frequency-tuning by currents occurs at constant orbital radius, so an exceptional agility is anticipated. To test this, we have inserted an oscillator in a microwave interferometer to apply abrupt current variations while time resolving its emission. Using frequency shift keying, we show that the oscillator can switch between two stabilized frequencies differing ...
Tópico(s): Physics of Superconductivity and Magnetism
2009 - American Institute of Physics | Applied Physics Letters
Produção Nacional
A. B. Henriques, Mauricio Manfrini, P. H. O. Rappl, E. Abramof,
The band-edge optical absorption in EuTe is studied in the framework of the $5d$ conduction band atomic model. Both relaxed antiferromagnetic order, and ferromagnetic order induced by an external magnetic field, were analyzed. For ferromagnetic arrangement, the absorption is characterized by a hugely dichroic doublet of narrow lines. In the antiferromagnetic order, the spectrum is blueshifted, becomes much broader and weaker, and dichroism is suppressed. These results are in excellent qualitative ...
Tópico(s): Iron-based superconductors research
2008 - American Physical Society | Physical Review B
Produção Nacional
A. B. Henriques, A. Wierts, Mauricio Manfrini, G. Springholz, P. H. O. Rappl, E. Abramof, A. Y. Ueta,
The band-edge optical absorption of EuTe and EuSe, grown by molecular beam epitaxy, was measured, using circularly polarized light, in the Faraday configuration, at $T=1.8\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. In thin layers (less than $0.4\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m}$), a doublet of absorption lines could be observed, with a full width at half maximum of about $50\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ in EuTe and $80\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ in EuSe. The lines ...
Tópico(s): Phase-change materials and chalcogenides
2005 - American Physical Society | Physical Review B
Mauricio Manfrini, Joo-Von Kim, S. Petit, W. Van Roy, Liesbet Lagae, C. Chappert, T. Devolder,
Tópico(s): ZnO doping and properties
2013 - Nature Portfolio | Nature Nanotechnology
Werner Boullart, D. Radisic, Vasile Paraschiv, Sven Cornelissen, Mauricio Manfrini, Koichi Yatsuda, Eiichi Nishimura, Tetsuya Ohishi, Shigeru Tahara,
In this paper we report on the patterning challenges for the integration of Spin-Transfer Torque Magneto-Resistive- Random-Access Memory (STT MRAM). An overview of the different patterning approaches that have been evaluated in the past decade is presented. Plasma based etching, wet echting, but also none subtractive pattering approaches are covered. The paper also reports on the patterning strategies, currently under investigation at imec.
Tópico(s): Magnetic and transport properties of perovskites and related materials
2013 - SPIE | Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE
T. Devolder, K. Garcia, Guillaume Agnus, Mauricio Manfrini, S. Cornelissen, Tai Min,
We studied state of the art perpendicularly magnetized tunnel junctions to identify performance improvement opportunities. The free layer has both a low damping and a large anisotropy. Conversely, the perpendicular remanence of the reference layer requires its encapsulation and its coupling with the hard layer. The weak pinning and low damping of the reference layer may make it prone to fluctuations induced by spin-torque. The combined optimization of the interface anisotropies on both sides of ...
Tópico(s): Magnetic and transport properties of perovskites and related materials
2013 - American Institute of Physics | Applied Physics Letters
Massimo Mongillo, Daniele Chiappe, Goutham Arutchelvan, Inge Asselberghs, Marta Perucchini, Mauricio Manfrini, Dennis Lin, Cedric Huyghebaert, Iuliana Radu,
We report on the electrical characterization of synthetic, large-area MoS2 layers obtained by the sulfurization technique. The effects of dielectric encapsulation and localized defect states on the intrinsic transport properties are explored with the aid of temperature-dependent measurements. We study the effect of dielectric environment by transferring as-grown MoS2 films into different dielectrics such as SiO2, Al2O3, HfO2, and ZrO2 with increasing dielectric permittivity. Electrical data are ...
Tópico(s): Ferroelectric and Negative Capacitance Devices
2016 - American Institute of Physics | Applied Physics Letters
Mauricio Manfrini, Adrien Vaysset, Danny Wan, Eline Raymenants, Johan Swerts, Siddharth Rao, Odysseas Zografos, Laurent Souriau, Khashayar Babaei Gavan, Nouredine Rassoul, D. Radisic, M. Cupak, M. Dehan, Şafak Sayan, Dmitri E. Nikonov, Sasikanth Manipatruni, Ian A. Young, D. Mocuta, Iuliana Radu,
With the rapid progress of spintronic devices, spin-logic concepts hold promises of energy-delay conscious computation for efficient logic gate operations. We report on the electrical characterization of domain walls in interconnected magnetic tunnel junctions. By means of spin-transfer torque effect, domains walls are produced at the common free layer and its propagation towards the output pillar sensed by tunneling magneto-resistance. Domain pinning conditions are studied quasi-statically showing ...
Tópico(s): Quantum and electron transport phenomena
2018 - American Institute of Physics | AIP Advances
Adrien Vaysset, Mauricio Manfrini, Dmitri E. Nikonov, Sasikanth Manipatruni, Ian A. Young, Iuliana Radu, Aaron Thean,
The functionality of a cross-shaped Spin Torque Majority Gate (STMG) is primarily limited by the pinning of a domain wall (DW) at the center of the device. Here, an analytical model is built to calculate the conditions for such a pinning and to deduce the operating range. The assumptions of the model and the conclusions are validated by micromagnetic simulations. The total magnetic energy of the DW state is derived. By minimizing this energy with respect to two degrees of freedom, the DW stability ...
Tópico(s): Ferroelectric and Negative Capacitance Devices
2017 - American Institute of Physics | Journal of Applied Physics
Adrien Vaysset, Odysseas Zografos, Mauricio Manfrini, D. Mocuta, Iuliana Radu,
Spin Torque Majority Gate (STMG) is a logic concept that inherits the non-volatility and the compact size of MRAM devices. In the original STMG design, the operating range was restricted to very small size and anisotropy, due to the exchange-driven character of domain expansion. Here, we propose an improved STMG concept where the domain wall is driven with current. Thus, input switching and domain wall propagation are decoupled, leading to higher energy efficiency and allowing greater technological ...
Tópico(s): Ferroelectric and Negative Capacitance Devices
2018 - American Institute of Physics | AIP Advances
R. M. Otxoa, S. Petit, Mauricio Manfrini, Iuliana Radu, Aaron Thean, Joo-Von Kim, T. Devolder,
We study the magnetization dynamics in a nanocontact magnetic vortex oscillators as function of temperature. Low temperature experiments reveal that the dynamics at low and high currents differ qualitatively. At low currents, we excite a temperature independent standard oscillation mode, consisting of a gyrotropic motion of a vortex about the nanocontact in the free layer. Above a critical current, a sudden jump in the frequency is observed, which occurs with a substantial increase of the frequency ...
Tópico(s): Quantum and electron transport phenomena
2015 - Elsevier BV | Journal of Magnetism and Magnetic Materials
Eline Raymenants, Adrien Vaysset, Danny Wan, Johan Swerts, S. Van Beek, Odysseas Zografos, Dmitri E. Nikonov, Sasikanth Manipatruni, Ian A. Young, D. Mocuta, Iuliana Radu, Marc Heyns, Mauricio Manfrini,
The development of low-power spintronic computation would open new paths for advanced logic nodes. It could utilize a ferromagnetic free layer shared by multiple magnetic tunnel junctions to cascade spin-coherent information. The basic component of this device would be a magnetic tunnel junction with an extended free layer. Here, we study the magnetization dynamics of such a system. One or multiple intermediate resistance levels are observed during spin-torque-induced magnetization reversal. Micromagnetic ...
Tópico(s): Ferroelectric and Negative Capacitance Devices
2018 - Institute of Physics | Journal of Physics D Applied Physics
R. M. Otxoa, Mauricio Manfrini, T. Devolder, Joo-Von Kim, W. Van Roy, Liesbet Lagae, C. Chappert,
We study the frequency, linewidth, and power of spin torque driven vortex oscillators, based on a nanocontacted spin-valve (SV). The oscillation frequency strongly decreases with the contact size, and increases with the current. The power delivered by the oscillator is not quadratic with the current, in contrast with the behavior expected from the rigid vortex model (RVM). The linewidth is almost independent of the current at low current and does not strongly depend on the nanocontact size. We compare ...
Tópico(s): Force Microscopy Techniques and Applications
2011 - Wiley | physica status solidi (b)
Danny Wan, Mauricio Manfrini, Adrien Vaysset, Laurent Souriau, Lennaert Wouters, Arame Thiam, Eline Raymenants, Şafak Sayan, Julien Jussot, Johan Swerts, Sébastien Couet, Nouredine Rassoul, Khashayar Babaei Gavan, Kristof Paredis, Cedric Huyghebaert, Monique Ercken, Christopher J. Wilson, D. Mocuta, Iuliana Radu,
Magnetic tunnel junctions (MTJs) interconnected via a continuous ferromagnetic free layer were fabricated for Spin Torque Majority Gate (STMG) logic. The MTJs are biased independently and show magnetoelectric response under spin transfer torque. The electrical control of these devices paves the way to future spin logic devices based on domain wall (DW) motion. In particular, it is a significant step toward the realization of a majority gate, even though further downscaling may be required. To our knowledge, ...
Tópico(s): Semiconductor materials and devices
2018 - Institute of Physics | Japanese Journal of Applied Physics
Rémy Soucaille, Joo-Von Kim, T. Devolder, S. Petit, Mauricio Manfrini, W. Van Roy, Liesbet Lagae,
We study a spin torque oscillator based on magnetic vortices hosted by a pseudo spin valve, and generated and confined by a nanocontact configuration. In addition to the standard functioning modes of such spin torque oscillators, we present evidence for field and current conditions leading to a novel extinction regime, where the oscillator response is transiently quenched. We model the dynamics analytically for two non-interacting vortices, one in each magnetic layer. The similarity of their trajectories ...
Tópico(s): Molecular Junctions and Nanostructures
2017 - Institute of Physics | Journal of Physics D Applied Physics
T. Devolder, Joo-Von Kim, S. Petit, R. M. Otxoa, C. Chappert, Mauricio Manfrini, W. Van Roy, Liesbet Lagae,
We study the starting up phase of a current-controlled oscillator based on a magnetic vortex orbiting around a nanocontact in a spin-valve. From the idle state, current pulses down to a few nanoseconds can create the vortex, which is detected through the electrical signature of its steady-state gyration. Two ns are needed to reach the in-current equilibrium. The process can then be described by an Arrhenius law, with an activation energy that is consistent with the Oersted-field-induced separation ...
Tópico(s): Physics of Superconductivity and Magnetism
2011 - IEEE Magnetics Society | IEEE Transactions on Magnetics
T. Devolder, Joo-Von Kim, Mauricio Manfrini, G. Hrkac, P. Crozat, Liesbet Lagae, T. Schrefl, Claude Chappert,
The passage of spin-polarized currents through magnetic nanocontacts can lead to the excitation of self-sustained vortex oscillations in the free layer of a spin-valve stack. These oscillations involve the large amplitude translational motion of the vortex core about the contact region, with oscillation frequencies typically in the 200-500 MHz range. Here, we present a detailed experimental study of such current-driven vortex oscillations. In particular, we show that the oscillation mode is possible ...
Tópico(s): Quantum and electron transport phenomena
2009 - SPIE | Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE
Hung-Li Chiang, Tzu-Chiang Chen, Ming-Yuan Song, Yu‐Sheng Chen, Jung-Piao Chiu, Katherine Chiang, Mauricio Manfrini, Jin Cai, W. J. Gallagher, Tahui Wang, C.H. Diaz, H.‐S. Philip Wong,
To increase the density of magnetoresistive random access memory (MRAM) beyond the 1T1MTJ MRAM cell in use today, the design space for 1S1MTJ MRAM array is analyzed by cooptimizing both selectors and MTJs. Current low-resistance MTJs for 1T1MTJ MRAM are not suitable for 1S1MTJ MRAM. Threshold-type selectors would induce a strong read disturb on the MTJ due to the snapback voltage (VTH-VHOLD) when the selector is turned on. Also, exponential-typeselectors would degrade the read margin (RM) due to its ...
Tópico(s): Magnetic properties of thin films
2020 - Institute of Electrical and Electronics Engineers | IEEE Transactions on Electron Devices