Enhanced magnetic anisotropy energy density for superparamagnetic particles of cobalt

Bj, Hickey; Ma, Howson; Greig, D.; Wiser, Nathan

doi:10.1103/physrevb.53.32

Cited by 37 publications

(21 citation statements)

References 11 publications

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“…For typical laboratory experiments, ln(τm/τ0) is on the order of 25 [41]. For the observed blocking temperature, Tb = 14 K, we obtain an activation barrier KV of 0.30 eV, which coincides with the reported spin pairing interaction [9] and is on the same order as the average splitting of energy levels with 6-8 states per eV near the Fermi energy given above.…”

Section: Epr Observation Of a Blocking Temperaturesupporting

confidence: 79%

“…For a cluster radius of ca. 0.5 nm we obtain K ≈ 0.6 eV nm −3 (1 × 10 9 erg•cm −3 ) which is even larger than the value of 1 × 10 8 erg•cm −3 reported for nanometer size granular Co20Ag80 and Co25Ag75 (indices are percent composition) and two orders of magnitude larger than for bulk fcc cobalt (4 × 10 6 erg•cm −3 ) [40], but it was pointed out that, for such small particles, the anisotropy energy is more a surface than a volume property [41]. It appears that it is straightforward to explain the temperature-dependence of the magnetization in Figure 5 based on what is known about classical superparamagnetic nanoparticles with a single macroscopic superspin.…”

Section: Epr Observation Of a Blocking Temperaturementioning

confidence: 72%

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Magnetic Properties and the Superatom Character of 13-Atom Platinum Nanoclusters

Roduner

Jensen

2015

Magnetochemistry

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13-atom platinum nanoclusters have been synthesized quantitatively in the pores of the zeolites NaY and KL. They reveal highly interesting magnetic properties like high-spin states, a blocking temperature, and super-diamagnetism, depending heavily on the loading of chemisorbed hydrogen. Additionally, EPR active states are observed. All of these magnetic properties are understood best if one considers the near-spherical clusters as analogs of transition metal atoms with low-spin and high-spin states, and with delocalized molecular orbitals which have a structure similar to that of atomic orbitals. These clusters are, therefore, called superatoms, and it is their analogy with normal atoms which is in the focus of the present work, but further phenomena, like the observation of a magnetic blocking temperature and the possibility of superconductivity, are discussed.

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Section: Epr Observation Of a Blocking Temperaturesupporting

confidence: 79%

Section: Epr Observation Of a Blocking Temperaturementioning

confidence: 72%

Magnetic Properties and the Superatom Character of 13-Atom Platinum Nanoclusters

Roduner

Jensen

2015

Magnetochemistry

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“…The blocking Previous studies have demonstrated that the magnetic anisotropy energy density depends on properties such as particle shape and surface texture as well as the stresses in the particle, rather than being an intrinsic property of a superparamagnetic nanoparticle [50]. The same phenomenon was observed for the necklace-like FePt-Au HNCs, as shown in Fig.…”

Section: Magnetic Propertiessupporting

confidence: 62%

Controlled synthesis and multifunctional properties of FePt-Au heterostructures

Hou

Gao

2011

Nano Res.

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In this work, FePt-Au heterostructured nanocrystals (HNCs) such as tadpole-, dumbbell-, bead-, and necklace-like nanostructures were synthesized by a facile heteroepitaxial growth of Au NCs onto FePt nanorods (NRs). A study of the growth mechanism revealed that the morphology control of the final products can be correlated with the adsorption sites of hydrogen onto the FePt NRs, which can be manipulated by the amount of the forming gas (Ar/7% H 2 ) added. Not only the optical characteristic and magnetic properties of the intrinsic materials were retained in the products, but also the FePt-Au HNCs showed the tunable multifunctional properties resulted from the interactions between Au and FePt. Moreover, for methanol oxidation, the FePt-Au HNCs exhibited enhanced catalytic activity and CO tolerance on the catalyst surface compared to commercial Pt catalysts. It is worth noting that as multifunctional units, the FePt-Au HNCs also possess a heterogeneous surface, which could potentially enable their site-specific functionalization for targeting or imaging purposes in biomedical applications. More interestingly, the catalytic properties of the FePt-Au HNCs also endow this material with application potentials in nanocatalysis.

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“…In addition, surface effects, including both structural changes and electronic hybridization effects, can significantly modify the magnetic moments of the magnetic component and the anisotropy [183]. For instance, comparing FePt-Au heterodimers with FePt particles reveals that blocking temperature of heterodimers (25 K) is reduced from 40 K to 25 K as a result of anisotropy decrease and surface texture changing [90,184]. However, it has been shown that, while depending on the surface termination, an increasing anisotropy of this system is possible [183].…”

Section: Tailored Properties Of Selected Heterodimersmentioning

confidence: 99%

Magnetic-Plasmonic Heterodimer Nanoparticles: Designing Contemporarily Features for Emerging Biomedical Diagnosis and Treatments

2019

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Magnetic-plasmonic heterodimer nanostructures synergistically present excellent magnetic and plasmonic characteristics in a unique platform as a multipurpose medium for recently invented biomedical applications, such as magnetic hyperthermia, photothermal therapy, drug delivery, bioimaging, and biosensing. In this review, we briefly outline the less-known aspects of heterodimers, including electronic composition, interfacial morphology, critical properties, and present concrete examples of recent progress in synthesis and applications. With a focus on emerging features and performance of heterodimers in biomedical applications, this review provides a comprehensive perspective of novel achievements and suggests a fruitful framework for future research.

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Enhanced magnetic anisotropy energy density for superparamagnetic particles of cobalt

Cited by 37 publications

References 11 publications

Magnetic Properties and the Superatom Character of 13-Atom Platinum Nanoclusters

Magnetic Properties and the Superatom Character of 13-Atom Platinum Nanoclusters

Controlled synthesis and multifunctional properties of FePt-Au heterostructures

Magnetic-Plasmonic Heterodimer Nanoparticles: Designing Contemporarily Features for Emerging Biomedical Diagnosis and Treatments

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