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Full-Text Articles in Physics

Magnetoelectronics With Magnetoelectrics, Christian Binek, Bernard Doudin Dec 2004

Magnetoelectronics With Magnetoelectrics, Christian Binek, Bernard Doudin

Christian Binek Publications

Magnetoelectric films are proposed as key components for spintronic applications. The net magnetic moment created by an electric field in a magnetoelectric thin film influences the magnetization state of a neighbouring ferromagnetic layer through exchange coupling. Pure electrical control of magnetic confi gurations of giant magnetoresistance spin valves and tunnelling magnetoresistance elements is therefore achievable. Estimates based on documented magnetoelectric tensor values show that exchange fields reaching 100 mT can be obtained. We propose a mechanism alternative to current-induced magnetization switching, providing access to a wide range of device impedance values and opening the possibility of simple logic functions.


Training Of The Exchange-Bias Effect: A Simple Analytic Approach, Christian Binek Jul 2004

Training Of The Exchange-Bias Effect: A Simple Analytic Approach, Christian Binek

Christian Binek Publications

raining of the exchange bias effect in antiferro-/ferromagnetic heterostructures is considered in the theoretical framework of spin configurational relaxation, which is activated through consecutively cycled hysteresis loops. The corresponding exchange bias fields, µ0 HEB(n), reveal relaxation from the initial state, n = 1, of high antiferromagnetic interface magnetization to the equilibrium state of reduced magnetization in the limit of large n. The evolution of µ0HEB vs n is calculated with the help of a discretized Landau-Khalatnikov equation, where the continuous time parameter is replaced by the loop index n. The result reveals the origin ...


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 ...


Extrinsic Control Of The Exchange Bias, Christian Binek Jan 2004

Extrinsic Control Of The Exchange Bias, Christian Binek

Christian Binek Publications

A new control mechanism for the exchange bias effect in magnetic heterostructures is proposed. It takes advantage of the magnetoelectric effect which takes place in the antiferromagnetic pinning layer. In contrast with the pioneering AC measurements of the magnetoelectric effect, we investigate the magnetic response of the prototypical magnetoelectric compound Cr2O3 on static electric fields. The linear dependence of the magnetic moment on the applied axial electric field and the temperature dependence of the corresponding slopes αshort parallel are measured by DC SQUID magnetometry. The contribution of the field-induced surface magnetization and its impact on the exchange bias effect is ...


Magneto-Thermal Behavior Of A Granular Fecl2–Fe Heterostructure, Sarbeswar Sahoo, Christian Binek, Wolfgang Kleemann Jan 2004

Magneto-Thermal Behavior Of A Granular Fecl2–Fe Heterostructure, Sarbeswar Sahoo, Christian Binek, Wolfgang Kleemann

Christian Binek Publications

A granular system consisting of ferromagnetic single-domain Fe particles in an antiferromagnetic FeCl2 matrix was prepared by coevaporation in an ultra-high vacuum environment. The structural and magnetic properties were investigated by X-ray diffractometry and superconducting quantum interference device magnetometry, respectively. The heterostructure combines the properties of superparamagnetic Fe granules and the antiferromagnetism of the FeCl2 matrix. In addition, dipolar interaction-induced giant moments are observed below the Néel temperature of the FeCl2 matrix. The thermomagnetic properties of the giant moments are studied.