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Magnetic

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Full-Text Articles in Physical Sciences and Mathematics

Superspin Glass Behaviour Of Interacting Ferromagnetic Nanoparticles In Discontinuous Magnetic Multilayers, Christian Binek Mar 2012

Superspin Glass Behaviour Of Interacting Ferromagnetic Nanoparticles In Discontinuous Magnetic Multilayers, Christian Binek

Christian Binek

Discontinuous magnetic multilayers [Co80Fe20(t)/Al2O3(3nm)]10 with t = 0.9 and 1.0nm are studied by SQUID magnetometry and ac susceptibility. Owing to dipolar interaction the superparamagnetic cluster systems undergo collective glass-like freezing upon cooling. While both samples exhibit very similar glass temperatures Tg » 45 K and critical exponents zn » 10 and g » 1.4 as obtained from the temperature dependencies of the relaxation time, t, and the nonlinear susceptibility, c3, dynamical scaling reveals different critical exponents, b(0.9nm) »1.0 and b(1.0nm) » 0.6, respectively.


Light Diffraction By Field-Induced Non-Periodic Magnetic Domain Structures In Fecl2, Christian Binek Mar 2012

Light Diffraction By Field-Induced Non-Periodic Magnetic Domain Structures In Fecl2, Christian Binek

Christian Binek

The magnetic-field-induced mixed phase of the meta magnet FeCl2 gives rise to reduced transmittivity of circularly polarized light. Within the framework of the diffraction theory of thin random magnetic phase gratings and the assumption of field-dependent refractive indices of the antiferromagnetic domains the field dependence of the transmission is perfectly modeled.


Random-Field Critical And Spin-Flop Behavior Of The Anisotropic Heisenberg Antiferromagnet Fe0.9mg0.1br2 In Axial Magnetic Fields, Christian Binek Mar 2012

Random-Field Critical And Spin-Flop Behavior Of The Anisotropic Heisenberg Antiferromagnet Fe0.9mg0.1br2 In Axial Magnetic Fields, Christian Binek

Christian Binek

Faraday optical measurements on the dilute hexagonal antiferromagnet Fe0.85Mg0.15Br2 in an external axial field reveal a spin-flop phase line ending at a multicritical point (Tm=8.1 K, Hm=1050 kA m-1) and crossover from random-exchange to random-field Ising criticality with an exponent Phi =1.40+or-0.04 in the vicinity of TN=11.1 K. Cusp-like behaviour of the specific heat at TN is discussed in view of recent Monte Carlo results.


Magnetic And Transport Properties Of The V2– Vi3 Diluted Magnetic Semiconductor Sb2_Xmnxte3, Jeffrey Dyck, P. Svanda, P. Lostak, J. Horak, W. Chen, C. Uher Dec 2003

Magnetic And Transport Properties Of The V2– Vi3 Diluted Magnetic Semiconductor Sb2_Xmnxte3, Jeffrey Dyck, P. Svanda, P. Lostak, J. Horak, W. Chen, C. Uher

Jeffrey Dyck

We have measured electrical and magnetic properties of single crystals of Sb2_xMnxTe3 with x =0 – 0.045 at temperatures of 2 K to 300 K. Hall effect measurements indicate that each manganese atom donates approximately one hole to the valence band. The magnetic susceptibility is paramagnetic down to 2 K, and both Curie–Weiss and Brillouin analyses show that manganese substitutes for Sb and takes the Mn2+ state with S=5/2. Contrary to the case of III–V host matrices, manganese does not stimulate ferromagnetic order in the family of bulk layered V2– VI3 diluted magnetic semiconductors, at least in the range of …