Exchange Bias Training Effect in GdBaCo{sub 2}O{sub 5.5} Cobaltite
- Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences (Russian Federation)
The nature of the training effect in exchange bias compounds, which consists in a decrease in the exchange bias field H{sub EB} under magnetic field cycling, is clarified. It is shown that the training effect in GdBaCo{sub 2}O{sub 5 + δ} cobaltite with δ ≈ 0.5 is caused by a decrease in magnetization. Depending on time, magnetization M(t) decreases sharply after the first cycle and slowly in subsequent N cycles. A direct relationship (proportionality) is established between the decrease in the magnetization M(t) of ferromagnetic particles and the change of the field H{sub EB}(t). It is assumed that the cooling of a sample in a magnetic field gives rise to small (single-domain) and large ferromagnetic clusters in an antiferromagnetic environment. The sharp decrease in M(t) and H{sub EB}(t) and the deviation of the function H{sub EB}(N) from the well-known power-law relation ΔH{sub EB} ∝ N{sup –1/2} with N > 1 is explained by the transformation of large ferromagnetic clusters into a multidomain state under magnetic field cycling. The results are consistent with the phenomenological model of Meiklejohn and Bean, which predicts a linear dependence of the exchange bias on the ferromagnetic magnetization of a ferromagnet/antiferromagnet structure.
- OSTI ID:
- 22917799
- Journal Information:
- Journal of Experimental and Theoretical Physics, Journal Name: Journal of Experimental and Theoretical Physics Journal Issue: 2 Vol. 128; ISSN JTPHES; ISSN 1063-7761
- Country of Publication:
- United States
- Language:
- English
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