Abstract
High-resolution anisotropic magneto-resistance measurement (AMR) was used to detailed study the training effect in exchange biased CoO/Co bi-layer. The sample was cooled to 10 K from room temperature in the magnetic cooling field of 4000 Oe. Then we used 1500 Oe declined perturbation field to pin the magnetization orientation of the FM layer. The perturbation field forms certain angle Θ with the cooling field direction in-plane to re-induce the untrained state. The dependence of the untrained state on the angle between the direction of perturbation field and cooling field has been investigated. The AMR results reveal that the re-induced degree of untrained state is strongly correlated to the angle Θ. The exchange bias field HE for different Θ has been determined from the AMR results, which is in apparent agreement with the Meiklejohn-Bean model. The recover degree of untrained state is the largest when the angle is 75°, which is different from the traditional view point that untrained state should be the maximum when it is perpendicular. The training effect is related to the FM spin orientation, which can induce the change of the interfacial AFM spin reorientation with different angles.
Highlights
Since Meiklejohn and Bean discovered exchange bias [1] this effect has obtained considerable interesting both technologically and scientifically because of its application in spintronics [2]
The training effect is related to the FM spin orientation, which can induce the change of the interfacial AFM spin reorientation with different angles
The above features prompt us to undertake a new refit for the sample-hold of physics property measurement system (PPMS), which make the perturbation field
Summary
Since Meiklejohn and Bean discovered exchange bias [1] this effect has obtained considerable interesting both technologically and scientifically because of its application in spintronics [2]. Exchange bias (EB) is typically set by field cooling the anti-ferromagnetic (AFM) and ferromagnetic (FM) bi-layer through the Néel temperature and is an interfacial coupling effect, as well as often associated with training effect, enhancement of coercive and so on. The training effect mechanism is important to help understand the exchange bias [3]. The reappearance of untrained state will promote us obtain the training effect mechanism. In this case, if the applied magnetic field forms different angle with the cooling field, the transport properties of the system will be important to reflect the restoring of the untrained state and the change of the AFM bulk spin structure. The above features prompt us to undertake a new refit for the sample-hold of physics property measurement system (PPMS), which make the perturbation field
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