Study of the onset of a long-range ferromagnetic order in an ensemble of small particles with giant magnetic moments

Interacting ferromagnetic nanoparticles in discontinuousCo80Fe20/AKleemann1, Petracic2, Binek3 et al. 2001Phys. Rev. B201111511View full textAdd to dashboardCite

“…Notably, the dispersionless part of Ј( f ,T) is unrelated to the loss function, Љ( f ,T). This is at variance with a recently reported 19 Ј( f ,T) curve in a 3D granular system exhibiting two peaks.…”

“…Since both of them were accompanied by sizeable losses, their assignment 19 to a SFM-SSG transition sequence appears doubtful. It should be noticed that the data shown in Fig.…”

Superferromagnetism on a two-dimensional array of magnetic nanodots: an Ising model approximation

“…Eq. (16) shows that the exchange coupling is strongly dependent upon the dot arrangement, increasing for higher dot volume fraction as expected, due to a decrease on the interdot distance. Fig.…”

“…Investigation of magnetic nanodot systems have shown a transition from a superparamagnetic regime to a super spin-glass state, and addressed evidences for a transition to a superferromagnetic (SFM) order [5,6]. As far as we know evidences of the SFM ordering was first addressed on goethite nanodots [7], but it has been recently found on several systems containing MNDs deposited on metallic or insulator non-magnetic substrates [4][5][6][7][8][9][10][11][12][13][14][15][16]. It has been pointed out in the literature that such a transition can be achieved through dipole-dipole interaction [4] or through an exchange coupling between the magnetic nanodot moments [5,11,17,18].…”

Collective dynamics and ferromagnetic order in random planar arrays of magnetic granules

“…Unlike the well understood case of isotropic exchange coupling, the orientational ground state is here critically sensitive to the spatial configuration of elements. 2,11,12 A common mean-field approach to a ͑diluted͒ dipolar system considers each moment m n in the point n to feel an effective ͑static͒ local field by other moments: Other important factors are the applied magnetic field 8,9 and the finite size ͑stray field͒ corrections to the point dipole approximation.…”