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Exchange bias

Selected Works

Christian Binek

Articles 1 - 4 of 4

Full-Text Articles in Physics

Freezing Field Dependance Of The Exchange Bias In Uniaxial Fef2-Copt Heterosystems With Perpendicular Anisotropy, Christian Binek Mar 2012

Freezing Field Dependance Of The Exchange Bias In Uniaxial Fef2-Copt Heterosystems With Perpendicular Anisotropy, Christian Binek

Christian Binek

The exchange bias effect is measured for the first time in FeF2–CoPt heterosystems with perpendicular anisotropy. The exchange previous field exhibits a strong dependence on the axial previous freezing field. This behavior is explained in terms of the microscopic spin structure at the interface, which is established on cooling to below TN. We calculate the dependence of the spin structure on the previous freezing field within the framework of an Ising model. It takes into account the Zeeman energy as well as an antiferromagnetic exchange coupling between the adjacent layers at the interface.


Isothermal Low-Field Tuning Of Exchange Bias In Epitaxial Fe/Cr2o3/Fe, S. Sahoo, T. Mukherjee, K. Belashchenko, Christian Binek Mar 2012

Isothermal Low-Field Tuning Of Exchange Bias In Epitaxial Fe/Cr2o3/Fe, S. Sahoo, T. Mukherjee, K. Belashchenko, Christian Binek

Christian Binek

Moderate dc magnetic fields of less than 1 T allow tuning the exchange bias in an epitaxially grown Fe 10 nm/Cr2O3 2.7 nm/Fe 10 nm trilayer between negative and positive bias fields. Remarkably, this tunable exchange bias is observed at least up to 395 K which exceeds the Néel temperature of bulk Cr2O3 (307 K). The presence of spontaneous exchange bias and the absence of training effects at room temperature suggest the existence of stable interface moments independent of antiferromagnetic long range order in Cr2O3. Furthermore, the coercivity remains constant, independent of the exchange bias field. In ...


Dynamic Enhancement Of The Exchange Bias Training Effect, Sarbeswar Sahoo, Srinivas Polisetty, Christian Binek, Andreas Berger Mar 2012

Dynamic Enhancement Of The Exchange Bias Training Effect, Sarbeswar Sahoo, Srinivas Polisetty, Christian Binek, Andreas Berger

Christian Binek

Exchange bias in coupled magnetic thin films and its accompanying training effect are fundamental interface phenomena with significant impact in spintronic applications. Both effects are well known in heterosystems of ferro- and antiferromagnetic thin films. Here, we report on the dynamic enhancement of the training effect in an exchange coupled bilayer of soft and hard ferromagnetic materials. Training is referred to as a gradual change of the bias field, which evolves upon cycling the soft layer through consecutive hysteresis loops. Its dynamic enhancement is observed with increasing sweep rate of the applied magnetic field from quasistatic to the fully dynamic ...


Piezomagnetism In Epitaxial Cr2o3 Thin Films And Spintronic Applications, Sarbeswar Sahoo, Christian Binek Mar 2012

Piezomagnetism In Epitaxial Cr2o3 Thin Films And Spintronic Applications, Sarbeswar Sahoo, Christian Binek

Christian Binek

Stress-induced perturbation of the antiferromagnetic long-range order in epitaxially grown Cr2O3 thin films gives rise to pronounced piezomagnetism and a significant reduction of the antiferromagnetic ordering temperature. The temperature dependence of the piezomagnetic moment measured by superconducting quantum interference device magnetometry reveals a power law behaviour with a critical exponent 2B=0.66 in accordance with the Ising anisotropy of a three-dimensional system. The observed shift of the Neel temperature allows estimating the internal lateral stress which is in excellent agreement with an independent estimate based on the elastic properties of Cr2O3 and the lattice mismatch at the interface between ...