Positive exchange bias of EuO1−x films

Spontaneous magnetization reversal and positive exchange bias effect in CoFeSiB/FeCrO3 heterostructures

“…Here, M is measured from 380 K down to 5 K in both zero-field-cooled (M ZFC ) and field-cooled modes (M FC ) with the magnetic field applied in the plane of the film. M increases as the temperature decreases, and it is clear that there is no magnetic anomaly in the measured temperature range from 5 K to 380 K; in fact, the T C and T N of the FM and AFM layers are well above room temperature (bulk FCO shows T N ∼ 560 K) [17,18]. From the curve, an evident bifurcation below 50 K can be observed; furthermore, the M ZFC and M FC curves do not merge in the temperature range from 5 K to 300 K. A plot of ∆M (=M FC −M ZFC ) vs T(K), as shown in the inset of figure 2(a), indicates that the blocking temperature may be above 380 K. It is found that M vs T for a higher magnetic field (5 kOe) has dominant bifurcation below 20 K, but ∆M (=M FC −M ZFC ) vs T does not merge in the measured temperature range.…”

“…In certain systems a spontaneous loop shift was observed without the need for a field-cooling (FC) process; such an unusual effect was indeed noted experimentally in a few bulk and thin film heterostructures [15][16][17] but there is no satisfactory theory to explain the spontaneous EB effect. It is interesting to note that the FM Ni layer can undergo all three versions of the EB phenomenon [16] due to the fact that its interface gets modified by the nature of the underlying AFM spin structure of FeF 2 .…”

Controlling the Magneto-Optical Response in Ultrathin Films of EuO1–xvia Interface Engineering with Ferroelectric BaTi2O5

“…The exchange bias is plotted vs temperature in Figure 3a and exhibits a positive exchange bias below the Curie temperature, which was recently attributed to the antiferromagnetic coupling between two ferromagnetic sources, namely, the Eu 2+ 4f spins and the bound magnetic polarons, in polycrystalline EuO 1−x thin films free from EuSi 2 . 52 Positive exchange bias has been attributed to antiferromagnetic alignment at an interface of two spin regions. 53,54 In the present study, the origin of the positive exchange bias below the Curie temperature is difficult to pinpoint.…”