Revealing the reversible rotation of magnetization in exchange-coupled composite media switching - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Applied Physics Letters Année : 2009

Revealing the reversible rotation of magnetization in exchange-coupled composite media switching

Résumé

We present a study of the magnetic reversal mechanism for exchange coupled composite perpendicular media, i.e., hard granular layer/exchange-coupling layer ͑ECL͒/soft layer ͑SL͒ systems, without soft underlayer. Using a vibrating sample magnetometer, the out-of-plane and in-plane components of the magnetization are monitored simultaneously, while sweeping an external out-of-plane magnetic field. The in-plane signal reveals the reversible rotation of the magnetization during the switching process. The amplitude of this rotation is correlated with the variations in coercivity and angular dependence of the remanent coercivity for different ECL and SL thicknesses. One of the main challenges currently faced by the hard disk drive industry is maintaining both writability and magnetic stability within magnetic volumes so small that the magnetic anisotropy energy responsible for stabilizing the direction of the magnetization becomes comparable to the energy of thermal fluctuations at room temperature. While for single layer perpendicular media, writability and stability are correlated through the magnetocrystalline anisotropy, it has been demonstrated in recent years that adding a soft magnetic layer ͑SL͒ to the usual hard granular layer ͑HL͒, in a so-called exchange-coupled composite ͑ECC͒ media can improve the writability-to-stability ratio. 1,2 Theoretical models have been developed for the proposed incoherent reversal process in ECC media 3,4 and several experimental demonstrations of the advantages of ECC media with respect to recording performance have been published. 5–9 Most of these reports focus on defining optimum properties for the SL as well as for the interfacial exchange-coupling between the HL and the SL. However, only a few experiments have been performed for the purpose of understanding the fundamental nature of the incoherent reversal or confirming the theoretical predictions in actual perpendicular media structures. Here we study an ECC system grown without a soft underlayer ͑SUL͒ in order to investigate the incoherent reversal process. The absence of the SUL and the use of a vibrating sample magnetometer ͑VSM͒ to sense both the out-of-plane and in-plane component of the magnetization simultaneously , allows observing and quantifying the tilt of the SL magnetization during the field induced reversal. We prepared a series of samples with different SL thicknesses in order to study the effect of SL thickness on the degree of magnetiza-tion tilt in the ECC system. Finally, we demonstrate the origin of the " reversibility " observed during the minor loop analysis reported in previous experiments. 7,10,11
Fichier principal
Vignette du fichier
ECC_Margulies_media_APL2009.pdf (405.65 Ko) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

hal-01345326 , version 1 (13-07-2016)

Identifiants

Citer

Thomas Hauet, S.H. Florez, D Margulies, Y Ikeda, B Lengsfield, et al.. Revealing the reversible rotation of magnetization in exchange-coupled composite media switching. Applied Physics Letters, 2009, ⟨10.1063/1.3270535͔⟩. ⟨hal-01345326⟩
17 Consultations
92 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More