Interfacial magnetic coupling between Fe nanoparticles in Fe–Ag granular alloys

Alonso, Javier; Fdez-Gubieda, M. L.; Sarmiento, G. Sánchez; Chaboy, J.; Boada, Roberto; Prieto, A.; Haskel, D.; Laguna-Marco, M. A.; Lang, J. C.; Meneghini, Carlo; Barquı́n, L. Fernández; Neisius, Thomas; Orúe, I.

doi:10.1088/0957-4484/23/2/025705

Cited by 27 publications

(17 citation statements)

References 56 publications

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“…This approach previously used for a variety of systems [28,[34][35][36][37][38] does not fit our experimental data At T = 300 K, the Fe 15 Ag 85 (see top panel Figure 5) signal is very close to the structural one, being different in the region 0.015 ≤ Q ≤ 0.2Å −1 (highlighted in the top panel of Figure 6), which corresponds to the lengthscale 3.1 ≤ D ≤ 42 nm. This implies some short-range correlations among clusters of Fe nanoparticles (approximately between 2 and 15 closed packed Fe nanoparticles, bearing in mind that the size of a single MNP is around 2.7 nm), even in the most dilute case, at high temperatures and in absence of field, as was suggested in previous studies [4,8,10]. Cooling down to 150 K produces an increase of the magnetic signal in the whole Q-range, specially in the 0.01 ≤ Q ≤ 0.2Å −1 (3.1 ≤ D ≤ 63 nm, clusters spanning 2 to 23 Fe nanoparticles) region.…”

Section: Resultssupporting

confidence: 69%

“…Therefore the system is said in a blocked state when the acquisition time of the experimental technique is lower than the characteristic time or in the superparamagnetic (SPM) state when the acquisition time is greater than the characteristic time. Conversely when the interparticle interactions are very strong all of the nanoparticles could spontaneously align in a superferromagnetic (SFM) state [4][5][6][7][8]. In between these two extremes the superspin glass (SSG) state is found.…”

Section: Introductionmentioning

confidence: 99%

“…Many of the studies addressing magnetic interactions between nanoparticles have been performed using DC magnetization [8,10,11], AC susceptibility [4,9] and Mössbauer spectroscopy [3,[13][14][15]. Though incredibly powerful these macroscopic techniques cannot provide evidence on the structure of the magnetic entities.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic nanoscopic correlations in the crossover between a superspin glass and a superferromagnet

Venero

Rogers

Langridge

et al. 2016

Journal of Applied Physics

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Collective behaviors in which the magnetic response depends not only on the individual constituents but also on their interactions are an area of active research. We have produced a paradigmatic system where DC magnetron sputtered FexAg100−x (x = 15, 35) nanogranular films exhibit a crossover between a superspin glass (SSG) state and superferromagnetism (SFM), where direct exchange interactions overcome the frustration. The systems have been studied by non-linear susceptibility (NLS) and small angle neutron scattering (SANS). The NLS measurements were carried out between 2 and 300 K, in the absence of a biasing magnetic field, with frequencies spanning two decades. These measurements shed light on the complex nature of the interactions and the intricate relationship between direct exchange and long range magnetic interactions. The use of SANS allows us to estimate qualitatively the lengthscale of the magnetic correlations, and therefore identify a clear difference between the collective "supermagnetic" states (i.e. SSG and SFM) while establishing links between the structure and the magnetic interactions.

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Section: Resultssupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

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Magnetic nanoscopic correlations in the crossover between a superspin glass and a superferromagnet

Venero

Rogers

Langridge

et al. 2016

Journal of Applied Physics

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“…It must be finally underlined that the effect described here is purely related to the measurements conditions, since all the investigated temperatures lie below the Curie temperature of our PBA. Nevertheless, it is interesting to remember that, for compounds with temperature-dependent ordered magnetic states, XMCD measurements at different temperatures can also bring valuable information on the different states and on the transition between them (Chaboy et al, 1998;Bartolomé et al, 2005;Laguna-Marco et al, 2009;Carvallo et al, 2010;Boada et al, 2010b;Alonso et al, 2012).…”

Section: Figurementioning

confidence: 99%

A cookbook for the investigation of coordination polymers by transition metal K-edge XMCD

N'Diaye¹,

Bordage²,

Nataf³

et al. 2021

J Synchrotron Radiat

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In order to disentangle the physical effects at the origin of transition metal K-edge X-ray magnetic circular dichroism (XMCD) in coordination polymers and quantify small structural distortions from the intensity of these signals, a systematic investigation of Prussian blue analogs as model compounds is being conducted. Here the effects of the temperature and of the external magnetic field are tackled; none of these external parameters modify the shape of the XMCD signal but they both critically modify its intensity. The optimized experimental conditions, as well as a reliable and robust normalization procedure, could thus be determined for the study of the intrinsic parameters. Through an extended discussion on measurements on other XMCD-dedicated beamlines and for other coordination compounds, we finally provide new transition metal K-edge XMCD users with useful information to initiate and successfully carry out their projects.

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“…In our system, there is significant deviation between T irr and T f , especially for low fields (<10 mT), which indicates that the system is not magnetically homogeneous [ 41 ] although the material is compositionally homogeneous. This may indicate the existence of a magnetic cluster phase [ 42 ] in the sample. The magnetic inhomogeneity could be attributed to the interplay between ferromagnetic and antiferromagnetic interactions of Mn, resulting in short range magnetic (FM or AF) ordering.…”

Section: Resultsmentioning

confidence: 99%

Spontaneous Zero-Field Cooling Exchange Bias in Ni–Co–Mn–Sn Metamagnetic Heusler Sputtered Film

Alexandrakis

Rodríguez-Aseguinolaza

Anastasakos-Paraskevopoulos

et al. 2021

Nanomaterials

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Metamagnetic off-stoichiometric Heusler alloys are actively being investigated because of their great potential as magnetocaloric materials. These properties are intimately related to the nanoscale homogeneity of their magnetic properties, mainly due to a strong influence of the nature of the exchange interactions between Mn atoms on the magnetism of the alloys. In this work, a spontaneous exchange bias phenomenon on a Ni–Co–Mn–Sn metamagnetic Heusler sputtered film is presented and studied in detail. More particularly, a series of DC magnetization curves measured as a function of the temperature demonstrates that the system exhibits canonical spin glass-like features. After a careful study of the field-cooling and zero-field-cooling curves measured on this system, the existence of magnetic inhomogeneities is inferred, as a consequence of the competition between ferromagnetic and antiferromagnetic exchange interactions between Mn atoms. Further AC susceptibility measurements on this system demonstrate that the underlying exchange bias phenomenon can be attributed to a magnetic clusters model based on superferromagnetic-like interactions present in the film. These findings suggest that the spontaneous exchange bias exhibited by the studied system is a consequence of the formation of this superferromagnetic-like state.

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Interfacial magnetic coupling between Fe nanoparticles in Fe–Ag granular alloys

Cited by 27 publications

References 56 publications

Magnetic nanoscopic correlations in the crossover between a superspin glass and a superferromagnet

Magnetic nanoscopic correlations in the crossover between a superspin glass and a superferromagnet

A cookbook for the investigation of coordination polymers by transition metal K-edge XMCD

Spontaneous Zero-Field Cooling Exchange Bias in Ni–Co–Mn–Sn Metamagnetic Heusler Sputtered Film

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