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Christian Binek Publications

2002

Articles 1 - 4 of 4

Full-Text Articles in Physics

Magnetic Relaxation Phenomena In The Superspin-Glass System [Co80Fe20/Al2O3]10, Sarbeswar Sahoo, O. Petracic, Christian Binek, Wolfgang Kleemann, J. B. Sousa, Susana Cardoso De Freitas, P. P. Freitas Nov 2002

Magnetic Relaxation Phenomena In The Superspin-Glass System [Co80Fe20/Al2O3]10, Sarbeswar Sahoo, O. Petracic, Christian Binek, Wolfgang Kleemann, J. B. Sousa, Susana Cardoso De Freitas, P. P. Freitas

Christian Binek Publications

Relaxation and temperature cycles of thermoremanent magnetization, MTRM, in the superspin-glass phase of [Co80Fe20 (0.9 nm)/Al2O3 (3 nm)] 10 have been investigated. The relaxation of MTRM exhibits ageing phenomena. In negative temperature cycles for temperature steps larger than 1 K the magnetic state is retrieved (memory effect) on returning to the measurement temperature. This property is independent of the application of a field step during intermediate cooling. In positive temperature cycles the relaxation is suppressed after temporary heating. The observations are discussed in the light of both the droplet and ...


Training Of The Exchange-Bias Effect In Nio-Fe Heterostructures, A. Hochstrat, Christian Binek, Wolfgang Kleemann Sep 2002

Training Of The Exchange-Bias Effect In Nio-Fe Heterostructures, A. Hochstrat, Christian Binek, Wolfgang Kleemann

Christian Binek Publications

The training effect of a NiO(001)/Fe(110) heterostructure is studied from magnetic hysteresis loops measured by superconducting quantum interference device magnetometry. Consecutive hysteresis loops exhibit a decreasing exchange bias effect. This behavior is known as the training effect, which reflects the dependence of the exchange bias field on the antiferromagnetic interface magnetization. In order to evidence this dependence, we study the decrease of the total saturation magnetization of the heterostructure for an increasing number of hysteresis cycles. Assuming proportionality between the interface magnetization and the total saturation magnetization, the description of the data is consistent within the phenomenological ...


Domain Wall Relaxation, Creep, Sliding, And Switching In Superferromagnetic Discontinuous Co80Fe20/Al2O3 Multilayers, X. Chen, O. Sichelschmidt, Wolfgang Kleemann, Christian Binek, J.B. Sousa, Susana Cardoso De Freitas, P.P. Freitas Sep 2002

Domain Wall Relaxation, Creep, Sliding, And Switching In Superferromagnetic Discontinuous Co80Fe20/Al2O3 Multilayers, X. Chen, O. Sichelschmidt, Wolfgang Kleemann, Christian Binek, J.B. Sousa, Susana Cardoso De Freitas, P.P. Freitas

Christian Binek Publications

The ac susceptibility of a superferromagnetic discontinuous multilayer [Co80Fe20(1.4   nm)/ Al2O3(3   nm)]10 is measured as a function of temperature, frequency, and field amplitude and compared to static and dynamic hysteresis loops. Its properties are successfully mapped onto the predicted [T. Nattermann, V. Pokrovsky, and V. M. Vinokur, Phys. Rev. Lett. 87, 197005 (2001).] dynamical phase transitions, which link the relaxation, creep, sliding, and switching regimes of pinned domain walls.


Superspin-Glass Nature Of Discontinuous Co80Fe20/Al2O3 Multilayers, Sarbeswar Sahoo, O. Petracic, Christian Binek, Wolfgang Kleemann, J.B. Sousa, Susana Cardoso De Freitas, P.P. Freitas Mar 2002

Superspin-Glass Nature Of Discontinuous Co80Fe20/Al2O3 Multilayers, Sarbeswar Sahoo, O. Petracic, Christian Binek, Wolfgang Kleemann, J.B. Sousa, Susana Cardoso De Freitas, P.P. Freitas

Christian Binek Publications

Ferromagnetic single domain particles of CoFe in discontinuous magnetic multilayers [Co80Fe20 (0.9 nm)/ Al2O3(3 nm)] 10 reveal spin-glass ordering below Tg=43.6 K as evidenced by the criticality of the nonlinear susceptibility. Dynamic critical scaling yields exponents zν=8.0 and β=1.0 in both zero and weak applied field, where an Almeida-Thouless line is encountered. In fields exceeding 2 mT a crossover into a chiral glass regime seems to occur.