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KR: Fachgruppe Kristallographie

KR 5: Poster Multiferroics (Joint Session of MA, DF, DS, KR, TT)

KR 5.80: Poster

Dienstag, 15. März 2011, 10:45–13:00, P2

Effect of spin structure transition in IrMn on the CoPd\ IrMn perpendicular exchange biased system. — •Muhammad Bilal Janjua and Gernot Güntherodt — II. Physikalisches Institut A, RWTH Aachen University, Aachen, Germany

The exchange bias (EB) phenomenon is studied in MBE grown Pd(10 nm)\CoPd(x=8,16,30 nm)\IrMn(15 nm)\Pd(4 nm) samples, which exhibit a perpendicular anisotropy of Co22Pd78. These samples are field cooled along the out-of-plane direction and hysteresis loops are measured along both the out-of-plane and in-plane directions. It is observed that there is a transition temperature where the out-of-plane EB becomes greater than the in-plane EB. This behavior of EB is an evidence of the change in the spin structure of the given system, which is also revealed by the magnetization versus temperature measurements of the exchange biased and of the sole IrMn samples. It is found that with increasing temperature there is a spin structure transition in Ir25Mn75 (15nm) related to the 2Q to 3Q transition in the bulk, which is responsible for the increase in out-of-plane EB. A vertical shift in the hysteresis loop is also observed in these exchange biased samples at low temperatures (T<50 K).