Hopkinson effect in an assembly of single domain particles- thermonagnetic curves of Nd2Fe14B-type ribbons

Попов, О. Н.; Mikhov, M.

doi:10.1016/0304-8853(88)90131-x

Cited by 49 publications

(17 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This mechanism is obviously inapplicable to the case of single-domain particles. However, a thermomagnetic eect which is quite similar to the Hopkinson eect has been experimentally observed in most of the amorphous magnetic materials as well as in some spin glasses where the existence of multi-domain particles is questionable or even practically impossible [2]. In Nd 2 Fe 14 B-type ribbons the existence of a maximum in the thermomagnetic curves of thermally demagnetized samples in low elds was connected with the processes of irreversible rotation of magnetic moments of non-interacting uniaxial single domain particles according to the Stoner Wohlfarth model [2,4].…”

Section: Introductionmentioning

confidence: 74%

See 1 more Smart Citation

Hopkinson-Like Effect in Single-Crystalline CdCr₂Se₄and Cd[Cr_1.89Ti_0.08]Se₄

et al. 2012

View full text Add to dashboard Cite

The static (dc) and dynamic (ac) magnetic measurements of CdCr2Se4 and Cd[Cr1.89Ti0.08]Se4 showed their ferromagnetic properties with a Curie temperature TC ≈ 130 K and revealed on the real component of ac susceptibility curve, the peaks near TC at 200 Oe, 450 Oe and 1 kOe, characteristic for the Hopkinson ones. The meaningful reduction of saturation moment to 4.73 µB/f.u. for Cd[Cr1.89Ti0.08]Se4 suggests the diamagnetic conguration of Ti ions, which dilutes the ferromagnetic sublattice of Cr ones and causes reducing of the energy losses visible on the imaginary components of ac susceptibility curve. Close for zero values of higher susceptibility harmonics above TC are pointing out to the lack of the spin uctuations in the paramagnetic state.

show abstract

Section: Introductionmentioning

confidence: 74%

“…This behavior is commonly called the Hopkinson eect [2]. The accepted explanation [3] of this eect is based only on domain wall motion.…”

Section: Introductionmentioning

confidence: 99%

Hopkinson-Like Effect in Single-Crystalline CdCr₂Se₄and Cd[Cr_1.89Ti_0.08]Se₄

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Due to heating soft magnetic sample the domain-wall mobility increases and consequently the magnetic susceptibility increases as well. This idea is obviously inapplicable to the case of singledomain particles [2][3][4][5]. We observed however the Hopkinson effect in many χ(T ) dependences of the hexagonal (Ba, Sr) ferrite samples, or in (not only single domain) particle ferrite samples.…”

Section: Introductionmentioning

confidence: 76%

“…As example the critical single domain size for spherical isolated particles has been predicted to be 0.5µm [2] for Ba ferrite and nearly 1 µm for NiZn ferrite at room temperature. For a particle with a volume V and with uniaxial symmetry, the anisotropy energy can be written in the form A(θ) = KV sin 2 θ .…”

Section: Overview Of the Super-paramagnetic Relaxationmentioning

confidence: 99%

Hopkinson Effect Study in Spinel and Hexagonal Ferrites

Sláma¹,

Šoka²,

Grusková³

et al. 2011

Journal of Electrical Engineering

View full text Add to dashboard Cite

The magnetic susceptibility shows a Hopkinson peak just below the Curie temperature T C when heating the selected hexagonal and spinel ferrite samples. It is proposed that this peak can be associated with a transition from stable magnetic state to super-paramagnetic relaxation above the blocking temperature up to the T C . The Hopkinson effect results are compared with SEM micrographs of both studied hexagonal and spinel ferrites.K e y w o r d s: Hopkinson effect, super-paramagnetic relaxation, blocking temperature, spinel and hexagonal ferrite

show abstract

“…As shown in [15]- [20], low-field thermomagnetic curves (i.e., magnetization versus temperature dependence at a fixed low magnetic field) for disordered systems of single-domain particles can exhibit Hopkinson-type behavior, due to the specific temperature dependencies of both the spontaneous magnetization and the magnetic anisotropy constant . In fact, the Hopkinson-type effect (existence of a peak in the initial thermomagnetic curves near the Curie temperature ) observed in many different systems and related to different mechanisms, is always governed by the temperature dependence of magnetic anisotropy.…”

Section: Introductionmentioning

confidence: 97%