We present experimental evidence on the physical origin of a magnetic dead layer (MDL) in manganite nanoparticles. The studied nanoparticles constitute wall La0.67Sr0.33MnO3 and La0.67Ca0.33MnO3 nanotubes. Magnetic properties analysis high resolution transmission electron microscopy show shell approximately 2 nm thickness with different from core. In this atoms are noncrystalline array that perfectly explains 50% reduction magnetization compared to bulk. Moreover, we internal structure MDL...

The role of agglomeration and magnetic interparticle interactions in heat generation ferrofluids an ac field is still unclear, with apparent discrepancy between the results presented literature.In this work, we measured generating capability agglomerated ferrite nanoparticles a non-invasive f = 100 kHz H 0 13 kA m -1 .The were morphologically magnetically characterized, specific absorption rate (SAR) for our presents clear dependence on diameter nanoparticles, maximum SAR 48 W g 15 nm.Our...

Magnetic properties of antiferromagnetic (AFM) ${\text{Cr}}_{2}{\text{O}}_{3}$ nanoparticles have been studied as a function the nanoparticle size. The synthesized present an ellipsoidal shape with major axis approximately 170 nm and minor that increases synthesis temperature from 30 to 70 nm. By magnetization electron paramagnetic resonance experiments, we obtained parameters characterize AFM system. We found N\'eel temperature, ${T}_{N}$, spin-flop field, ${H}_{\text{SF}}$, increase...

We show that ferromagnetic/paramagnetic La${}_{0.75}$Sr${}_{0.25}$MnO${}_{3}$/LaNiO${}_{3}$ multilayers present an unexpected magnetic exchange-bias effect (EBE), observed in field-cooled magnetization loops. The field and the enhancement of coercivity vanish around 50 K. demonstrate oxidation state Ni Mn cations changes from Mn${}^{3+}$-Ni${}^{3+}$ to Mn${}^{4+}$-Ni${}^{2+}$ layers close interface probed by x-ray absorption spectroscopy measurements. variation valence states is accompanied...

We introduce a nanoparticle-mesoporous oxide thin film composite (NP-MOTF) as low-cost and straightforward sensing platforms for surface-enhanced Raman Spectroscopy (SERS). Titania, zirconia, silica mesoporous matrices templated with Pluronics F-127 were synthesized via evaporation-induced self-assembly loaded homogeneously dispersed Ag nanoparticles by soft reduction or photoreduction. Both methods give rise to uniform reproducible signals using 4-mercaptopyridine probe molecule. Details on...

In this work we describe the synthesis and characterization of maghemite nanoparticles obtained by a new synthetic route. The material was synthesized using triethylamine as coprecipitation agent in presence organic ligand N,N′-bis(3,5-di-tert-butyl-catechol)-2,4-diaminotoluene (LCH3). Mössbauer spectrum at 4 K shows typical hyperfine parameters Transmission Electron Microscopy images reveal that have mean diameter 3.9 nm narrow size distribution. AC magnetic susceptibility zero field...

We report the magnetic properties of antiferromagnetic Cr2O3 from bulk material down to 6 nm nanoparticles. have found a decrease in lattice parameters and cell volume when size diminishes. On contrary, anisotropy constant, Keff, shows nonmonotonic behavior. The Keff decreases its value, minimum near ϕ∼30 displays an important increase for smaller sizes. analyzed dependence terms magnetocrystalline surface contributions, we fitted evolution on basis phenomenological model taking into account...

Magnetic domain walls can be described within the general framework of disordered elastic systems, which accounts well for most their dynamical and geometrical properties. Beyond theoretical predictions, authors report here unexpected features observed under application alternating square pulses. In particular, magneto-optical images show that evolve toward strongly distorted shapes concomitantly with a reduction area. The evolution morphology is characterized, underlying physics discussed.

We present measurements of the anisotropic magnetoresistance (AMR) La0.75Sr0.25MnO3 films deposited on (001) SrTiO3 substrates, and a model that describes experimental results. The model, based electronic structure manganites plus spin–orbit coupling, correctly accounts for dependence AMR direction current to crystalline axes. measure an order 10 − 3 I parallel [100] axis crystal vanishing , in agreement with predictions. Further, we calculate planar Hall effect show its connection AMR.

The magnetic properties of ∼1.5 nm Co nanoparticles embedded in a diamagnetic Al2O3 or antiferromagnetic (AFM) Cr2O3 matrix were investigated. For matrix, typical behavior weakly interacting is observed, characterized by superparamagnetic regime and progressive blocking particle moments centered at ⟨TB⟩=14 K. On the other hand, when are immersed very different was found. system shows large irreversibility field-cooling/zero-field-cooling magnetization curves much larger coercivity observed...

Designing magnetic materials for potential applications based on domain wall motion requires the knowledge of relationship between physical properties and phenomenological parameters characterizing dynamics. We address in this work study magnetic-field-driven within creep regime a prototypical metallic Pt/Co/Pt stack with perpendicular anisotropy. By controlling deposition characteristics, different are achieved, giving rise to parameters. Those found collapse single linear dependence all...

We studied the transport and magnetic properties of low-doped manganite films after different oxygenation processes. The oxygen content was adjusted by postdeposition annealing at pressures times. For all samples we observed an increase in Curie temperature remnant magnetization with content. In general, for decreasing number vacancies, under expansive strain become more homogeneous their electrical resistivity decreases. A metal-insulator transition is induced highly oxygenated grown on...

We report the precise control of tunneling magnetoresistance (TMR) in devices self-assembled core/shell Fe$_3$O$_4$/Co$_{1-x}$Zn$_x$Fe$_2$O$_4$ nanoparticles ($0\leq x\leq 1$). Adjusting magnetic anisotropy through content Co$^{2+}$ shell, provides an accurate tool to switching field between bistable states TMR. In this way, different combinations soft/hard and hard/soft configurations can be envisaged for optimizing with required magnetotransport response.

Understanding the effect of fabrication conditions on domain wall motion in thin films with perpendicular magnetization is a mandatory issue order to tune their properties aiming design spintronics devices based such phenomenon. In this context, present work intends show how different growth may affect prototypical system Pt/Co/Pt. The trilayers were deposited by dc sputtering, and parameters varied study Co thickness, substrate roughness, base pressure deposition chamber. Magneto-optical...

In this work we show the existence of closure domains in ${\mathrm{Fe}}_{0.8}{\mathrm{Ga}}_{0.2}$ thin films featuring a striped magnetic pattern and study effect domain arrangement on magnetotransport properties. By means x-ray resonant scattering, experimentally demonstrate presence such also estimate their sizes relative contribution to surface magnetization. Magnetotransport experiments that behavior magnetoresistance depends measurement geometry as well temperature. When electric...

In this work, an original route for ZnO nanostructured spherical colloids and their assembly into colloidal crystals are presented. The temporal evolution of crystal size shape was followed by X-ray diffraction the distribution scanning electron microscopy. These showed a change in dispersion with aging time. Early stage suspensions, narrow distribution, were settled to bottom dried slow evaporation rate obtain crystals. This provides new material future applications opalline photonic...

The angular dependence of the magnetoresistance effect has been measured on bicrystalline La0.75Sr0.25MnO3 films. measurements have performed an electronically lithographed Wheatstone bridge. study both and resistance single-crystalline grain-boundary regions samples allowed us to isolate two contributions low-field in manganites. One them is associated with spin–orbit effect, i.e. anisotropic ferromagnetic compounds, other one related spin-disorder at grain boundary. Complementary x-ray...

Magnetotransport properties of ${\mathrm{Fe}}_{0.8}{\mathrm{Ga}}_{0.2}$ films with stripe domains are studied. The anisotropic magnetoresistance dominates the low field behavior, which is extremely dependent on magnetic configuration. measured at different temperatures displays qualitatively behaviors depending measurement When stripes oriented along electric current, low-field changes sign temperature, while when perpendicular to current curves nearly temperature independent. A simple model...

The creep motion of domain walls driven by external fields in magnetic thin films is described universal features related to the underlying depinning transition. One key parameter this description roughness exponent characterizing growth fluctuations wall position with its longitudinal length scale. amplitude, which gives information about scale fluctuations, however, has received less attention. Albeit their relevance, experimental reports parameters, both and are scarce. We report here...

Combined electric- and magnetic-field control of magnetization orientation reversal is studied using anomalous Hall effect in an ultrathin ferromagnetic (Ga,Mn)As/(Ga,Mn)(As,P) bilayer. Its anisotropy results from the electrically tunable competition between in-plane out-of-plane anisotropies both layers. The magnetic hysteresis loop shape sensitive to bias electric field. In reversible part, electric-field variation found reorient reversibly magnetization. this case, direction follows easy...