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Abstract: During device manufacture, metal contamination has a large effect on silicon-based device performance. Of the available gettering techniques, helium implantation is widely used but the high fluence required is a major drawback. In this paper, the impact of F co-implantation on He implantation-induced defects has been carefully studied. Firstly, our results show that both interstitial and vacancy defects are present in the defect band for all implantation conditions. We show that F implantation may lead to cavity formation at high temperature as expected. The TEM observations also show that, at high temperature, the shape and size of the He-induced defects are significantly affected by the fluorine co-implantation. In particular, cavities are drastically modified by the addition of F, which promotes cavity growth. These results enable us to understand the defect interactions better and constitute a good background to gettering techniques for future device processing. [Copyright &y& Elsevier]

Abstract: Helium and hydrogen implantations lead to the formation of extended defects that strongly interact with impurities like metal and dopants, affecting significantly their final profiles. Even if the efficiency of this metal gettering technique is widely demonstrated in literature, the high dose requirement can be a drawback for industrial applications. Dose reduction becomes then crucial. In the smartcut® process, it has been shown that helium and hydrogen co-implantation leads to the expected dose decrease. The same idea was then applied for the gettering technique, keeping co-implantation doses below exfoliation threshold. After evidencing the impact of the H addition on cavities, this paper will focus on boron interactions with He–H induced defects. For this purpose, uniformly high doped (1018 B cm−3) P-type <111> wafers were used. He implantation at 40keV for a dose of 5 or 1×1016 He+ cm−2 followed or not by H implantation at 36keV for different doses were carried out. Samples were subsequently furnace annealed for 1h at temperatures ranging from 500 to 900°C. Transmission electron microscopy (TEM) observations allow us to monitor the defect evolution. Secondary ion mass spectrometry (SIMS) was used to follow the boron and hydrogen profiles while the spreading resistance profiling (SRP) gives the activation dependence with the implantation and the annealing temperature. This work enlightens the large impact of H on cavity growth and clarifies the interaction of B with extended defects in presence or absence of hydrogen. [Copyright &y& Elsevier]

For ferromagnetic (F)/antiferromagnetic (AF) nanodots contributions of AF spins to exchange bias is discussed. The relative weights of AF entities located at the dot edges, at the F/AF interface and in the AF grains were obtained by comparing the blocking temperature distribution of an array of nanodots with that of corresponding continuous film. Due to grain cutting, the grain size distribution is altered. We show here that the dot edges constitute additional locations for the formation of spin-glasslike AF regions at the F/AF interface. The result of patterning is thus twofold and weakens the dot ability to resist thermally activated magnetization reversal. [ABSTRACT FROM AUTHOR]

In this paper, we describe a new media for heat assisted magnetic recording at ultrahigh density. Thermal simulations were performed to optimize this media. It consists in a patterned porous silicon substrate on which magnetic multilayers are deposited by magnetron sputtering. Magnetic properties of these multilayers are compared to those of layers deposited on regular silicon substrate. Despite the very particular structure of porous silicon surface, no big differences are observed and magnetic properties of the multilayers are conserved. Writing tests will be performed on these media with heating tips. [ABSTRACT FROM AUTHOR]

High-quality In x Ga 1− x As layers with indium composition between 0.46 and 0.50 have been grown in a 300 mm industrial MOVPE reactor using ≤1 μm thin In x Ga 1− x As buffers on 2″ GaAs substrates. Aggressive grading of 3.7 to 3.8% misfit/μm, fast growth rates in the range of 0.2–2.2 nm/s and low growth temperatures of 530 °C and 450 °C were used. AFM reveals a significant difference in root mean square surface roughness of 3.6 nm (530 °C) versus 15.5 nm (450 °C). Cross-section TEM analysis shows that for both temperatures threading dislocations are effectively confined to the buffer region. However, at 450 °C phase separation is observed in the upper part of the structure. From plan-view TEM threading dislocation densities as low as 1×10 5 cm −2 and 4.5×10 5 cm −2 are estimated for growth at 530 °C and 450 °C, respectively. [ABSTRACT FROM AUTHOR]

The influence of the microstructure on the exchange bias properties of antiferromagnetic/ferromagnetic submicronic dots was investigated in arrays of IrMn/Co square dots of lateral dimensions ranging between 200 and 50�nm. IrMn grain size and distributions were tuned by changing the Cu buffer layer or IrMn thicknesses. Exchange bias variability was analysed through focused Kerr measurements on small groups of dots. The average exchange bias field in the patterned samples have similar values as in full sheet samples and with similar variations versus Cu and IrMn thicknesses. Concerning the exchange bias variability, an increase in variability was observed in the patterned samples caused by grain cutting at the dot edges during the patterning process. This increase in exchange bias variability is observed to be even more important in samples having large average grain sizes, particularly for small dots. These effects are correlated with the grain size distributions on full sheet samples. [ABSTRACT FROM AUTHOR]

Finite size effects on the exchange-bias properties of patterned antiferromagnetic/ferromagnetic (IrMn/Co) nanodots were investigated experimentally and by numerical simulations. Both the dot lateral dimension (200 × 200 nm2-50 × 50 nm2) and ferromagnetic layer thickness (2-25 nm) were varied. Two different behaviours were observed: single-shifted loops with coherent reversal for thin Co layers and double-shifted loops via a multidomain state during magnetization reversal for thicker Co. Atomistic simulations including magnetostatic interactions confirmed the existence of these two different regimes. MOKE measurements, focused on few dots, allowed a quantitative evaluation of dot-to-dot exchange-bias variability, which becomes particularly large in the regime of switching via multidomain state formation. This variability issue is of particular importance in the context of MRAM development and of magnetoresistive heads for hard-disk drives [ABSTRACT FROM AUTHOR]

Current-induced domain wall (DW) displacements in an array of ultrathin Pt/Co/AlOx wires with perpendicular magnetic anisotropy have been directly observed by wide field Kerr microscopy. DWs in all wires in the array were driven simultaneously and their displacement on the micrometer scale was controlled by the current pulse amplitude and duration. At the lower current densities where DW displacements were observed (j≤1.5×1012 A/m2), the DW motion obeys a creep law. At higher current density (j=1.8×1012 A/m2), zero-field average DW velocities up to 130±10 m/s were recorded. [ABSTRACT FROM AUTHOR]

An analytical model was developed to describe the current induced domain wall (DW) dynamics of a Bloch DW in the presence of an external transverse magnetic field. The model takes into account the DW deformation and the magnetization tilting in the domain. The model is compared to the results of micromagnetic simulation and an excellent agreement is obtained. In the steady state regime, the model shows that the domain tilting does not change the DW mobility. An external or current induced transverse magnetic field such as the Oersted or Rashba field can prevent the Walker breakdown leading to a higher domain wall velocity. [ABSTRACT FROM AUTHOR]

Current induced domain wall (DW) motion in perpendicularly magnetized nanostripes in the presence of spin orbit torques is studied. We show using micromagnetic simulations that the direction of the current induced DW motion and the associated DW velocity depend on the relative values of the field like torque (FLT) and the Slonczewski like torques (SLT). The results are well explained by a collective coordinate model which is used to draw a phase diagram of the DW dynamics as a function of the FLT and the SLT. We show that a large increase in the DW velocity can be reached by a proper tuning of both torques. [ABSTRACT FROM AUTHOR]

We employ a scanning nitrogen-vacancy-center microscope to perform stray field imaging of bubble magnetic domains in a perpendicularly magnetized Pt/Co/AlOx trilayer with 6Å of Co. The stray field created by the domain walls is quantitatively mapped with few-nanometer spatial resolution, with a probe-sample distance of about 100nm. As an example of application, we show that it should be possible to determine the Bloch or Néel nature of the domain walls, which is of crucial importance to the understanding of current-controlled domain wall motion. [ABSTRACT FROM AUTHOR]

Submicron magnetic tunnel junctions exhibiting perpendicular magnetic anisotropy have been prepared by sputtering. They associate a hard and a soft electrode based on Co/Pt multilayers, separated by an amorphous alumina barrier. The soft electrode is either free or exchange biased by an antiferromagnetic layer. The magnetoresistance ratio reaches 8% at room temperature after patterning junctions with diameter down to 200 nm. The macroscopic magnetic properties were investigated by extraordinary Hall effect and conventional magnetometry measurements. The magnetic moments of both electrodes are out of plane. Two well-separated switching fields allow the realization of well-defined parallel and antiparallel configurations of the magnetizations. [ABSTRACT FROM AUTHOR]

We present an analytic and numerical study of the creation of a unidirectional spin-wave emission in ultrathin ferromagnetic films sandwiched in an asymmetric layer stack. For this we extend the analytical description of spin waves in spin-wave waveguides by incorporating the influence of the interfacial Dzyaloshinskii-Moriya interaction on the spin-wave propagation. By exploring the model system Ni81Fe19/Pt, we show that it is possible to achieve a unidirectional spin-wave emission by combining wave-vector selective excitation sources with the frequency splitting that arises from the interfacial Dzyaloshinskii-Moriya interaction. Hereby, we focus on device feature sizes and spin-wave wavelengths that are compatible with state-of-the art excitation and detection schemes. We demonstrate that the presented analytical formalism allows for an approximate prediction of the nonreciprocal emission. [ABSTRACT FROM AUTHOR]

The miniaturization of complementary metal-oxide-semiconductor (CMOS) devices becomes increasingly difficult due to fundamental limitations and the increase of leakage currents. Large research efforts are devoted to find alternative concepts that allow for a larger data-density and lower power consumption than conventional semiconductor approaches. Spin waves have been identified as a potential technology that can complement and outperform CMOS in complex logic applications, profiting from the fact that these waves enable wave computing on the nanoscale. The practical application of spin waves, however, requires the demonstration of scalable, CMOS compatible spin-wave detection schemes in material systems compatible with standard spintronics as well as semiconductor circuitry. Here, we report on the wave-vector independent detection of short-waved spin waves with wavelengths down to 150 nm by the inverse spin Hall effect in spin-wave waveguides made from ultrathin Ta/Co8Fe72B20/MgO. These findings open up the path for miniaturized scalable interconnects between spin waves and CMOS and the use of ultrathin films made from standard spintronic materials in magnonics. [ABSTRACT FROM AUTHOR]

The dynamics of magnetic domain walls in ultrathin strip-patterned Pt/Co/AlOx samples with perpendicular easy axis has been studied experimentally under an easy-axis field, superposed to a hard-axis field oriented along the strip. The easy-axis field is large so that the domain walls move well beyond the creep regime. A chiral effect is observed where the domain wall velocity shows a monotonous and surprisingly large variation with an in-plane field. A micromagnetic analysis, combining analytic, one-dimensional, and two-dimensional simulations with structural disorder, shows that this behavior can be reproduced with a Dzyaloshinskii-Moriya interaction of the interfacial type, with due consideration of the dynamics of the tilt degree of freedom of the domain wall. The estimated effective value of this interaction (D ≈ -2.2mJ/m2 for a 0.6 nm Co thickness) is consistent with values obtained by other techniques. It is also shown, by micromagnetic analysis, that several modes and characteristic times occur in the dynamics of the tilt of such domain walls. [ABSTRACT FROM AUTHOR]

Controlled propagation speed of individual magnetic domains in metal channels at the room temperature is obtained via the non-volatile field effect associated with the switchable polarization of P(VDF-TrFE) (polyvinylidene fluoride-trifluoroethylene) ferroelectric polymer. Polarization domains directly written using conducting atomic force microscope probe locally accelerate/decelerate the magnetic domains in the 0.6nm thick Co film. The change of the magnetic domain wall velocity is consistent with the magnetic anisotropy energy modulation through the polarization upward/downward orientation. Excellent retention is observed. The demonstrated local non-destructive and reversible change of magnetic properties via rewritable patterning of ferroelectric domains could be attractive for exploring the ultimate limit of miniaturization in devices based on ferromagnetic/ferroelectric bilayers. [ABSTRACT FROM AUTHOR]

The nucleation of reversed magnetic domains in Pt/Co/AlOx microstructures with perpendicular anisotropy was studied experimentally in the presence of an in-plane magnetic field. For large enough in-plane field, nucleation was observed preferentially at an edge of the sample normal to this field. The position at which nucleation takes place was observed to depend in a chiral way on the initial magnetization and applied field directions. A quantitative explanation of these results is proposed, based on the existence of a sizable Dzyaloshinskii-Moriya interaction in this sample. Another consequence of this interaction is that the energy of domain walls can become negative for in-plane fields smaller than the effective anisotropy field. [ABSTRACT FROM AUTHOR]

Spin filtering effects in nano-pillars of Fe-MgO-Fe single crystalline magnetic tunnel junctions are explored with two different sample architectures and thin MgO barriers (thickness: 3-8 monolayers). The two architectures, with different growth and annealing conditions of the bottom electrode, allow tuning the quality of the bottom Fe/MgO interface. As a result, an interfacial resonance states (IRS) is observed or not depending on this interface quality. The IRS contribution, observed by spin polarized tunnel spectroscopy, is analyzed as a function of the MgO barrier thickness. Our experimental findings agree with theoretical predictions concerning the symmetry of the low energy (0.2 eV) interfacial resonance states: a mixture of Δ1-like and Δ5-like symmetries. [ABSTRACT FROM AUTHOR]

We investigated the magnetic switching of MgO/Co/Pt pillars with perpendicular magnetic anisotropy, for lateral pillar sizes from 30 μm to 2 lm and for Co layer thicknesses between 1.8 and 2.6 nm. For large pillars, both the coercivity and the remanent magnetization decrease for increasing Co thickness. For all Co thicknesses, the coercivity strongly increases upon decreasing the pillar size. A comparison with micromagnetic simulations shows that the change in coercivity is determined by size-dependent demagnetizing effects. Our results show that small pillars with perpendicular magnetization and a tunable coercivity can be fabricated from continuous layers with in-plane magnetization. [ABSTRACT FROM AUTHOR]

Non-volatile ferroelectric control of magnetic domains has been demonstrated in ultra-thin cobalt layers at room temperature. The sensitivity of magnetic anisotropy energy to the electronic structure in a few atomic layers adjacent to the interface allows for ferroelectric control of coercivity and magnetic domain dynamics. These effects have been monitored and quantified using magneto-optical Kerr effect. In particular, the regimes, where the ferroelectric domains enhance/inhibit the magnetic domain nucleation or increase/reduce domain wall velocity, have been explored. Thus, non-destructive and reversible ferroelectric domain writing provides a tool to define the magnetic domain paths, create nucleation sites, or control domain movement. [ABSTRACT FROM AUTHOR]

We show that the Dzyaloshinskii-Moriya interaction (DMI) can lead to a tilting of the domain wall (DW) surface in perpendicularly magnetized magnetic nanotracks when DW dynamics are driven by an easy axis magnetic field or a spin polarized current. The DW tilting affects the DW dynamics for large DMI, and the tilting relaxation time can be very large as it scales with the square of the track width. The results are well explained by an extended collective coordinate model where DMI and DW tilting are included. We propose a simple way to estimate the DMI in magnetic multilayers by measuring the dependence of the DW tilt angle on a transverse static magnetic field. These results shed light on the current induced DW tilting observed recently in Co/Ni multilayers with structural inversion asymmetry. [ABSTRACT FROM AUTHOR]

A correction to the article "High domain wall velocities induced by current in ultrathin Pt/Co/AlOx wires with perpendicular magnetic anisotropy" that was published online in the October 29, 2009 issue is presented.

Domain wall motion induced by nanosecond current pulses in nanostripes with perpendicular magnetic anisotropy (Pt/Co/AlO) is shown to exhibit negligible inertia. Time-resolved magnetic microscopy during current pulses reveals that the domain walls start moving, with a constant speed, as soon as the current reaches a constant amplitude, and no or little motion takes place after the end of the pulse. The very low "mass" of these domain walls is attributed to the combination of their narrow width and high damping parameter a. Such a small inertia should allow accurate control of domain wall motion by tuning the duration and amplitude of the current pulses. [ABSTRACT FROM AUTHOR]

We study the anisotropy of the spin and orbital magnetization of ultrathin Co layers characterized by structure inversion asymmetry, namely Pt/Co/AlOx trilayers with Co thicknesses between 0.6 and 2 nm. We use x-ray magnetic circular dichroism (XMCD) to probe the Co layer along two orthogonal measurement geometries. By combining transverse and collinear XMCD, we achieve a vector measurement of the Co spin and orbital magnetic moments. We find an enhanced and anisotropic orbital magnetic moment localized at the Co interface and verify the connection between the Co orbital moment anisotropy and the macroscopic magnetic anisotropy of the trilayer. These results provide a link between diverse interfacial phenomena originating from spin-orbit coupling, such as the Rashba effect and perpendicular magnetic anisotropy. Using simple considerations derived from tight-binding models, we show that the Rashba constant is proportional to the ratio between out-of-plane and in-plane orbital magnetic moments. [ABSTRACT FROM AUTHOR]

We have used time-resolved x-ray photoemission electron microscopy to investigate the magnetization dynamics induced by nanosecond current pulses in NiFe/Cu/Co nanostripes. A large tilt of the NiFe magnetization in the direction transverse to the stripe is observed during the pulses. We show that this effect cannot be quantitatively understood from the amplitude of the Oersted field and the shape anisotropy. High-frequency oscillations observed at the onset of the pulses are attributed to precessional motion of the NiFe magnetization about the effective field. We discuss the possible origins of the large magnetization tilt and the potential implications of the static and dynamic effects of the Oersted field on current-induced domain-wall motion in such stripes. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the SIMS beam induced roughness (BIR) in monocrystalline Si in presence of initial surface or bulk defects of nanometric size is studied. We follow the development of the BIR by monitoring the increase of Si2+ and SiO2 + signals during SIMS sputtering. The topography of the crater bottoms is measured at different steps of the evolution of the roughness using an atomic force microscope (AFM). We show that in presence of nanometric sized defects on the surface or in the bulk, the BIR develops far more rapidly than usual. It appears as soon as the crater reaches the defects and, as reported on Si free from any treatment, the same morphology evidencing waves perpendicular to the sputtering beam develops rapidly. This study of the behaviour of the BIR in presence of voluntarily introduced defects allows us to better understand the basic physical phenomena involved in its apparition. [Copyright &y& Elsevier]

• Double gate structures for channel material and gate stack characterization. • Easy and simple techniques based on the pseudo-MSOFET configuration. • Fast fabrication loop of double gate MOSFET. • Test structures for parameter extraction. • Double-gate pseudo-MOSFET for rapid material characterization. Pseudo-MOSFET delivers a fast, simple and reliable way of characterizing electrically SOI substrates without the need of full CMOS fabrication. However, the information refers to the back interface. Here, to probe the front interface, we extend the concept to a double-gate pseudo-MOSFET. The structure provides a pertinent test vehicle for the characterization and development of transistors channel and gate stack materials in a configuration similar to fully fabricated transistors. We show that the devices with undoped terminals need specialized modeling development to describe the double gate effect. Devices with doped terminals are immediately exploitable for parameter extraction. [ABSTRACT FROM AUTHOR]

Domain wall propagation has been measured in continuous, weakly disordered, quasi-two-dimensional, Ising-like magnetic layers that are subject to spatially periodic domain wall pinning potentials. The potentials are generated non-destructively using the stray magnetic field of ordered arrays of magnetically hard [Co/Pt]m nanoplatelets, which are patterned above and are physically separated from the continuous magnetic layer. The effect of the periodic pinning potentials on thermally activated domain wall creep dynamics is shown to be equivalent, at first approximation, to that of a uniform, effective retardation field, Hret, which acts against the applied field, H. We show that Hret depends not only on the array geometry but also on the relative orientation of H and the magnetization of the nanoplatelets. A result of the latter dependence is that wall-mediated hysteresis loops obtained for a set nanoplatelet magnetization exhibit many properties that are normally associated with ferromagnet/antiferromagnet exchange bias systems. These include a switchable bias, coercivity enhancement, and domain wall roughness that is dependent on the applied field polarity. [ABSTRACT FROM AUTHOR]

The magnetic properties of perpendicular exchange biased ferromagnetic (FM)/antiferromagnetic (AFM) [Pt/Co]n/IrMn systems were investigated by a new set-up combining element-selective soft x-ray holography and spectroscopy measurements. The holography experiments allow imaging the magnetization reversal of an exchange biased FM layer with an equivalent Co thickness below 5 nm in real space and in external magnetic fields, and provide direct evidence of its asymmetric nature. From the spectroscopy analysis, we have quantified the unpinned (pinned) uncompensated AFM moments, providing direct evidence of its parallel (antiparallel) alignment with respect to the FM moments. [ABSTRACT FROM AUTHOR]

The stray magnetic field of an array of hard ferromagnetic perpendicularly magnetized [Co/Pt]4 nanodots is used to nondestructively generate a periodic pinning potential for domain walls in an underlying [Pt/Co]2/Pt layer with perpendicular anisotropy. Pinning is evidenced using magneto-optical microscopy. The magnetic field (H) dependence of the average wall velocity in the presence of the periodic pinning potential is consistent with thermally activated creep, modified only by the addition of a uniform retarding field Hret, whose magnitude depends on the relative alignment of H and the dots' magnetizations. [ABSTRACT FROM AUTHOR]

Only a very few experimental techniques can address the microscopic magnetization reversal behavior of the different magnetic layers in a multilayered system with element selectivity. We present an element-selective study of ferromagnetic (FM) [Co/Pt]n multilayers with perpendicular anisotropy exchange-coupled to antiferromagnetic (AFM) FeMn and IrMn films performed with a new experimental set-up developed for both soft x-ray spectroscopy and holography imaging purposes. The spectroscopy analysis allows the quantification of the unpinned (pinned) uncompensated AFM moments, providing direct evidence of its parallel (antiparallel) alignment with respect to the FM moments. The holography experiments give a direct view of both FM and uncompensated AFM magnetic structures, showing that they replicate to each other during magnetization reversal. Remarkably, we show magnetic images for effective thicknesses as small as one monolayer. Our results provide new microscopic insights into the exchange coupling phenomena and explore the sensitivity limits of these techniques. Future trends are also discussed. [ABSTRACT FROM AUTHOR]

We have measured the field dependence of the AC magnetic susceptibility of a single crystal of the molecular nanomagnet Fe8. Accelerations in the magnetic relaxation are observed at the field values corresponding to levels crossings. Other anomalies are observed around 1.5 and 3.5 kOe. We propose that they are due to a resonant tunnel mechanism involving the first excited spin state. With a simplified two spins model we find that a sizeable tunnel splitting is calculated at anti-crossing between states belonging to S=10 and 9 multiplets. [Copyright &y& Elsevier]

We show that the spin-orbit torque induced magnetization switching in nanomagnets presenting Dzyaloshinskii-Moriya (DMI) interaction is governed by a chiral domain nucleation at the edges. The nucleation is induced by the DMI and the applied in-plane magnetic field followed by domain-wall propagation. Our micromagnetic simulations show that the dc switching current can be defined as the edge nucleation current, which decreases strongly with increasing amplitude of the DMI. This description allows us to build a simple analytical model to quantitatively predict the switching current. We find that domain nucleation occurs down to a lateral size of 25 nm, defined by the length scale of the DMI, beyond which the reversal mechanism approaches a macrospin behavior. The switching is deterministic and bipolar. [ABSTRACT FROM AUTHOR]

The electric (E)-field control of magnetic properties opens the prospects of an alternative to magnetic field or electric current activation to control magnetization. Multilayers with perpendicular magnetic anisotropy have proven to be particularly sensitive to the influence of an E-field due to the interfacial origin of their anisotropy. In these systems, E-field effects have been recently applied to assist magnetization switching and control domain wall (DW) velocity. Here we report on two new applications of the E-field in a similar material: controlling domain wall nucleation and stopping DW propagation at the edge of the electrode. [ABSTRACT FROM AUTHOR]