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Christian Binek Publications

Discontinuous

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Full-Text Articles in Physics

Superferromagnetic Domain State Dynamics In Discontinuous Cofe/Al2o3, Christian Binek Jan 2004

Superferromagnetic Domain State Dynamics In Discontinuous Cofe/Al2o3, Christian Binek

Christian Binek Publications

Magnetization hysteresis and AC susceptibility measurements were performed on the discontinuous metal–insulator multilayer [Co80Fe20(1.4 nm)/Al2O3(3 nm)]10. CoFe forms ferromagnetic single-previous domain term particles being embedded in the Al2O3 matrix. Due to strong dipolar inter-particle interactions a “previous superferromagnetic term” correlation of particle moments was previously stated. The dynamical magnetic properties of the superferromagnet can be understood in the framework of previous domain term wall motion in an impure ferromagnet. Kinetic simulations are employed, which are based on field and temperature-dependent previous domain term wall velocities. The magnetization hysteresis as well as the AC susceptibility ...


Magnetic States Of Discontinuous Co80fe20al2o3 Multilayers, Christian Binek Oct 2001

Magnetic States Of Discontinuous Co80fe20al2o3 Multilayers, Christian Binek

Christian Binek Publications

Discontinuous metal–insulator multilayers [Co80Fe20(t)/Al2O3(3 nm)]n were studied by SQUID magnetometry and AC susceptometry. CoFe forms ferromagnetic particles in the Al2O3 matrix. In this paper, we focus on the field dependence of the AC susceptibility of samples with t=1.3 nm. We find strong evidence for transitions from a superpara- to a superferromagnetic and, finally, to a reentrant superspin glass previous state.


Superspin Glass Behaviour Of Interacting Ferromagnetic Nanoparticles In Discontinuous Magnetic Multilayers, Christian Binek Oct 2000

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

Christian Binek Publications

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.