Size dependence of the spin-flop transition in hematite nanoparticles

Zysler, R.D.; Fiorani, D.; Testa, Alberto Maria; Suber, Lorenza; Agostinelli, E.; Godinho, M.

doi:10.1103/physrevb.68.212408

Cited by 171 publications

(141 citation statements)

References 18 publications

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“…The former tends to make spins direct themselves along ±z-axis, while the latter does spins lying in xy-plane [261]. [262][263][264][265][266][267][268]. Theoretical work showed that the Morin transition depends on a via adependent dipolar anisotropy term [260], and the size effect of T M 0 (D) has been induced by the change of the dipolar magnetic field with a lattice expansion [263,269,270].…”

Section: The Morin Transitionmentioning

confidence: 99%

Size Dependence of Structures and Properties of Magnetic Materials

Jiang¹,

Lang²

2007

TONANOJ

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Due to the involvement of high portion of atomic coordination imperfection in surfaces and interfaces, the properties of magnetic nanocrystals dramatically differ from that of the corresponding bulk counterparts, which have led to a surge in both experimental and theoretical investigations in the past decades. This review summarizes the studies for these size-dependent magnetic properties, and additional thermal or phase stabilities, and mechanical properties. To interpret the above phenomena, a thermodynamic model for the size dependence and interface dependences of these properties is described, which is based on Lindemann s criterion for melting, Mott s expression for the vibrational melting entropy, and Shi s model for the size-dependent melting temperature. The model without any adjustable parameter is confirmed by a large number of experimental results, and helps us to understand the structures and properties of the magnetic nanocrystals. Moreover, other theoretical works on the above properties are also mentioned and commented.

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Section: The Morin Transitionmentioning

confidence: 99%

Size Dependence of Structures and Properties of Magnetic Materials

Jiang¹,

Lang²

2007

TONANOJ

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“…Therefore, between T M and Neel temperature (T N ≈ 956K), an electron traveling in the basal plane will experience a ferromagnetically aligned situation. 12 In the nano-regime, the magnetic and structural properties of hematite are strongly influenced by particle size, [13][14][15] degree of crystallinity 16 and doping. [17][18][19] Doping of different metal ions or metal oxides into α-Fe 2 O 3 can improve the magnetic properties and will ameliorate the performance of the existing applications.…”

Section: Introductionmentioning

confidence: 99%

Enhanced coercivity in Co-doped α-Fe2O3 cubic nanocrystal assemblies prepared via a magnetic field-assisted hydrothermal synthesis

et al. 2017

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Ferromagnetic Co-doped α-Fe2O3 cubic shaped nanocrystal assemblies (NAs) with a high coercivity of 5.5 kOe have been synthesized via a magnetic field (2 kOe) assisted hydrothermal process. The X-ray diffraction pattern and Raman spectra of α-Fe2O3 and Co-doped α-Fe2O3 NAs confirms the formation of single-phase α-Fe2O3 with a rhombohedral crystal structure. Electron microscopy analysis depict that the Co-doped α-Fe2O3 NAs synthesized under the influence of the magnetic field are consist of aggregated nanocrystals (∼30 nm) and of average assembly size 2 μm. In contrast to the NAs synthesized with no magnetic field, the average NAs size and coercivity of the Co-doped α-Fe2O3 NAs prepared with magnetic field is increased by 1 μm and 1.4 kOe, respectively. The enhanced coercivity could be related to the well-known spin–orbit coupling strength of Co2+ cations and the redistribution of the cations. The size increment indicates that the small ferromagnetic nanocrystals assemble into cubic NAs with increased size in the magnetic field that also lead to the enhanced coercivity.

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“…The effect of substitution of Cr and Mn ions in GaFeO 3 manifests itself and can be delineated starting with suitable oxide precursors preferentially containing Cr (Mn) in the Ga or Fe site. It is noteworthy that Cr (Mn) substitution in the octahedral Fe (1,2) site of GaFeO 3 has marked effects on the structural parameters and magnetic properties, while substitution in the octahedral Ga 2 site has marginal effects [2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…The magnetic and structural properties of haematite are also affected by particle size [7,8], degree of crystallinity [9], pressure [10], doping [2][3][4][5][6], and mechanical alloying [11] due to its technological applications. It is noticed that depending upon milling conditions, structural phase transformations of nanostructured haematite to maghemite, magnetite and wüstite can be induced.…”

Section: Introductionmentioning

confidence: 99%

“…The magnetic properties of haematite in bulk form and as spherical nanoparticles have been intensively studied because they have various applications in magnetic storage devices, spin electronic devices, drug delivery, tissue repair engineering, and magnetic resonance imaging [7,8,[17][18][19]. In contrast to spherical nanoparticles, nanorods with their inherent onedimensional (1-D) shape anisotropy may exhibit unique magnetic behavior, which is significantly different from that of the bulk material [20,21].…”

Section: Introductionmentioning

confidence: 99%

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