Abstract
We report the observation of ferromagnetic (FM) and antiferromagnetic (AFM) interlayer exchange coupling (IEC) in GaMnAsP-based trilayer structures with out-of-plane magnetic anisotropy. Magnetization and anomalous Hall effect (AHE) measurements show well-resolved magnetization transitions corresponding to the two GaMnAsP layers. Minor loop measurements reveal a characteristic shift caused by IEC in all trilayer samples investigated. Interestingly, the FM IEC changes to AFM IEC for a trilayer with the thinnest (7 nm) top GaMnAsP layer as the temperature increases. The observation of temperature-induced transition of FM and AFM IEC in the same sample suggests the possibility of device applications by controlling the type of IEC in such GaMnAsP-based multilayers.
Highlights
Two-step hysteresis loops were observed for all trilayer samples during magnetization reversal in both SQUID and Hall resistance measurements, indicating that coercive fields of the two GaMnAsP layers in each trilayer are different
Different temperature dependences of coercive fields were observed for GaMnAsP layers with different thicknesses
In which the magnetization of one GaMnAsP layer remains fixed while the other GaMnAsP layer experiences a reversal of its magnetization, show a shift indicating the presence of FM IEC in all samples when measured at low temperatures
Summary
The 7 nm sample, shows a different and more interesting IEC behavior in the temperature regions below and above coercive field crossing, as seen in the relative shifts of the Up-ML and Down-ML in the 3rd column of Fig. 6. Note that the IEC conversion occurs as the temperatures increases over the coercive field crossing temperature This implies that the observed reversal of IEC with increasing temperature may be related to the change in the order in which magnetization switches in the two GaMnAsP layers, which is a unique phenomenon observed in our GaMnAsP-based multilayers. Even though further systematic investigation is still necessary for understanding of the cause of the observed IEC conversion, the present study shows that both FM and AFM IEC can be realized in a single GaMnAsP-based multilayer and, importantly, that it can be switched by controlling appropriate tuning parameters, making it of interest for devices that involve manipulation of magnetization
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