SEMINARIUM INSTYTUTOWE

Dnia: 25.04.2018 roku (środa)
o godzinie 13:00 w auli

referat pt.:

Zjawisko „exchange bias” w próbkach ceramicznych, nanocząstkach
i monokryształach złożonych tlenków o strukturze perowskitu

wygłosi

prof. dr hab. Andrzej Wiśniewski

Instytut Fizyki PAN, Warszawa

The exchange bias (EB) phenomenon was discovered in 1956 by Meiklejohn and Bean. It has been intensively studied in the last decades because of its importance for the magnetic information storage technologies.The EB effect manifests itself by shifts in the isothermal magnetization (M vs. H) curves along the field direction and sometimes along the magnetization axis, as well as by enhancement of the coercive field in field cooled processes. In general, the EB effect results from coupling between ferromagnetic (FM) spins and interfacial, uncompensated antiferromagnetic (AFM) spins, occurring during cooling of a FM-AFM system through the Néel temperature in applied magnetic field. A brief review of EB effect in ceramic samples, nanoparticles and single crystals of managanites, cobaltites, ruthenates and orthoferrites will be presented. In general, the most relevant common feature of these compounds, leading to an appearance of EB effect is an intrinsic phase separation. Parameters of EB may be very effectively tuned by even tiny change in chemical composition and moderate external hydrostatic pressure due to their impact on AFM/FM phase ratio.