Static critical exponents of the ferromagnetic transition in spin glass re-entrant systems

Haetinger, C; Ghivelder, L.; Schaf, J.; Pureur, P.

doi:10.1088/0953-8984/21/50/506006

Cited by 13 publications

(16 citation statements)

References 44 publications

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“…This diagram resembles that of a re-entrant spin glass (see for example [14]) where the system evolves from a paramagnetic state to a ferromagnetic one, and finally to a spin-glass-like state as the temperature decreases. The shape of the ZFC/FC curves of the present sample is very similar to that observed in the case of magnetically disordered systems, such as solid solutions or amorphous alloys [5,6,14,[40][41][42][43]. Chien et al [44] observed that Fe-Ag amorphous alloys with Fe concentrations around 45-50 at.% became paramagnetic above a Curie temperature in the range 200-250 K, close to T P2 .…”

Section: Magnetization Resultssupporting

confidence: 83%

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

Alonso¹,

Fdez-Gubieda²,

Sarmiento³

et al. 2011

Nanotechnology

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The role of the interface in mediating interparticle magnetic interactions has been analysed in Fe50Ag50 and Fe55Ag45 granular thin films deposited by the pulsed laser deposition technique (PLD). These samples are composed of crystalline bcc Fe (2–4 nm) nanoparticles and fcc Ag (10–12 nm) nanoparticles, separated by an amorphous Fe50Ag50 interface, occupying around 20% of the sample volume, as determined by x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), and high resolution transmission electron microscopy (HRTEM). Interfacial magnetic coupling between Fe nanoparticles is studied by dc magnetization and x-ray magnetic circular dichroism (XMCD) measurements at the Fe K and Ag L2,3 edges. This paper reveals that these thin films present two magnetic transitions, at low and high temperatures, which are strongly related to the magnetic state of the amorphous interface, which acts as a barrier for interparticle magnetic coupling.

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Section: Magnetization Resultssupporting

confidence: 83%

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

Alonso¹,

Fdez-Gubieda²,

Sarmiento³

et al. 2011

Nanotechnology

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“…We can thus not confirm a dimensional crossover. The data support the finding that systems where disorder is linked to magnetic canting and frustration cannot be characterized by a single set of exponents [43].…”

Section: Resultssupporting

confidence: 83%

Reversed interface effects in amorphous FeZr/AlZr multilayers

et al. 2014

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We report an anomalous enhancement of the critical temperature (T c ) when the thickness (d) of the magnetic layer is decreased from 60 to 20Å in amorphous FeZr/AlZr multilayers. Further reduction of the thickness causes a decrease of T c , as expected by finite-size scaling, while the magnetic moment decreases monotonically for all values of d. The increase of the critical temperature is attributed to a reversed interface effect where local changes in the nearest-neighbor distance and coordination number gives a higher effective magnetic coupling at the interfaces compared to the interior of the layer. We have successfully described the results within a model where such interface effects are combined with finite-size scaling.

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“…Nonuniversal values of critical exponents with β ≈ 0.55 have also been found in recent experimental studies 23 of the ferromagnetic transition in spin-glass re-entrant metallic alloys such as Au 0.81 Fe 0.19 .…”

Section: Discussionsupporting

confidence: 63%

“…Except for the Mo13.5 alloy, which has a spin-glass phase below T g =10 K, all the other samples gave quite reasonable values of the critical exponents. Nonuniversal values of critical exponents with β ≈ 0.55 have also been found in recent experimental studies 23 of the ferromagnetic transition in spin-glass re-entrant metallic alloys such as Au 0.81 Fe 0.19 .…”

Section: Discussionsupporting

confidence: 63%

Signature effects of spin clustering and distribution of spin couplings on magnetization behaviour in Ni–Fe–Mo and Ni–Fe–W alloys

Banerjee¹,

Singh²,

Majumdar³

et al. 2011

J. Phys.: Condens. Matter

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The spontaneous magnetization as a function of temperature is investigated for a number of disordered Ni-Fe-Mo and Ni-Fe-W alloys using superconducting quantum interference device magnetometry, with a focus on the low-T behavior as well as the critical exponents associated with the magnetic phase transition. While the low-T magnetization is found to be well described by Blochs T 3/2 law, an extraordinary enhancement of the spin-wave parameter B and the reduced coefficient B 3/2 =BT 3/2 C are observed with increasing Fe dilution as compared to conventional 3d ferromagnets, whereas the critical amplitudes are found to decrease systematically. Recent locally self-consistent calculations of finite-temperature spin dynamics in a generic diluted magnet provide an understanding in terms of two distinct energy scales associated with weakly coupled bulk spins in the FM matrix and strongly coupled cluster spins. In view of similar behaviour observed in diluted magnetic semiconductors and other ferromagnetic alloys, it is proposed that these distinctive features corresponding to the three important temperature regimes provide macroscopic indicators of signature effects of spin clustering on magnetization behaviour in disordered ferromagnets.

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Static critical exponents of the ferromagnetic transition in spin glass re-entrant systems

Abstract: The static critical phenomenology near the Curie temperature of the re-entrant metallic alloys Au 0.

Cited by 13 publications

References 44 publications

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

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

Reversed interface effects in amorphous FeZr/AlZr multilayers

Signature effects of spin clustering and distribution of spin couplings on magnetization behaviour in Ni–Fe–Mo and Ni–Fe–W alloys

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