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Christian Binek Publications

Cr

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Full-Text Articles in Physics

Magnetocaloric Properties Of Co/Cr Superlattices, Tathagata Mukherjee, Sarbeswar Sahoo, David J. Sellmyer, Christian Binek Apr 2009

Magnetocaloric Properties Of Co/Cr Superlattices, Tathagata Mukherjee, Sarbeswar Sahoo, David J. Sellmyer, Christian Binek

Christian Binek Publications

Nanostructured materials for refrigeration applications are experimentally realized by molecular beam epitaxial growth of Co/Cr superlattices using mean-field theoretical concepts as guiding principles. Magnetocaloric properties are deduced from measurements of the temperature and field dependence of the magnetization of our samples. More generally, the potential of artificial antiferromagnets for near room-temperature refrigeration is explored. The effects of intraplane and interplane exchange interactions on the magnetic phase diagram in Ising-type model systems are revisited in mean-field considerations with special emphasis on tailoring magnetocaloric properties. The experimental results are discussed in light of our theoretical findings, and extrapolations for future improved ...


Quenching Of The Exchange Bias Training In Fe/Cr2o3/Fe Trilayer, Sarbeswar Sahoo, Christian Binek Oct 2008

Quenching Of The Exchange Bias Training In Fe/Cr2o3/Fe Trilayer, Sarbeswar Sahoo, Christian Binek

Christian Binek Publications

Exchange bias (EB) and its associated training effects are studied in an epitaxial Fe(10 nm)/Cr2O3(2.7 nm)/Fe(10 nm) trilayer heterostructure grown by molecular beam epitaxy. The EB decreases linearly with increasing temperature from T = 5 K to T = 50 K. It changes sign and becomes positive within 50 K < T < 200 K, finally changing back to regular EB for T<200K up to the highest measured temperature of T = 395 K. Remarkably, the latter is far above the bulk Néel temperature TN = 307 K. EB training effects occur only at 5 K < T < 50 K. We show that this training can be quenched by subjecting the system to DC magnetic field, µ0HDC <= 7 T. The applied field most likely induces a temperature dependent spin-flop transition. Upon its removal the antiferromagnetic Cr2O3 pinning layer evolves uniformly into its quasi-equilibrium spin configuration thus leading to quasi-equilibrium EB.