Magnetoresistance of as-prepared samples of magnetic multilayers: A unified picture

Abstract

We discuss the magnetic-field dependence of the magnetoresistance MR͑H͒ of magnetic multilayers for samples in the as-prepared state ͑meaning the first time the magnetic field is swept͒, pointing out the importance of the electron-scattering mean-free path. We show that the value of MR͑0͒ in the as-prepared state is related to MR͑H͒ data for field-swept samples ͑meaning samples for which the magnetic field has been swept back and forth͒. We use this relationship to obtain the value of MR͑0͒ for an as-prepared sample. Our prediction agrees with the data.

Accessing different spin-disordered states using first-order reversal curves

“…[10][11][12] Prior experiments have revealed that the virgin state MR of an as-prepared sample can actually be significantly larger than that accessible after subsequent field cycling during a major loop measurement. 10,13 These experiments have demonstrated that while there is a high degree of correlated anti-parallel alignment across the NM spacer in the asprepared state, during a major loop measurement the degree of domain correlation becomes more random at the coercive field 10,13 leading to a reduction in the maximum achievable MR. Furthermore, other coupling mechanisms such as exchange coupling via pinholes, 14 Néel (orange peel) coupling, 15 and magnetostatically driven domain replication 16 are often present in spin valves and may also play a significant role.…”

“…A variety of techniques has been employed to study the microscopic domain configurations in heterogeneous multilayers, correlating with other magnetic properties, including, e.g., polarized neutron reflectometry, scanning electron microscopy with polarization analysis, and * randydumas@gmail.com † kailiu@ucdavis.edu element-specific x-ray magnetic dichroism [10][11][12]. Prior experiments have revealed that the virgin state MR of an asprepared sample can actually be significantly larger than that accessible after subsequent field cycling during a major loop measurement [10,13]. These experiments have demonstrated that, although there is a high degree of correlated antiparallel alignment across the NM spacer in the as-prepared state, during a major loop measurement the degree of domain correlation becomes more random at the coercive field [10,13], leading to a reduction in the maximum achievable MR.…”

Magnetization and magnetization reversal in epitaxial Fe/Cr/Co asymmetric spin-valve systems

“…This is, however, not always the case and as-prepared magnetic configurations of multilayers may irreversibly be modified via external field application, as reported for some other systems. [12][13][14] In our superlattices, the zero field as-grown state reveals a noncollinear magnetization configuration, which presumably results from the adjustment of magnetization directions in each consecutively deposited layer to stray fields generated by a set of domains in all previously deposited layers. The resulting metastable depth profile and lateral domain configuration cannot be recovered after saturation, but can be reproduced with a new set of samples.…”