Inhomogeneous magnetic field influence on magnetic properties of NiFe/IrMn thin film structures

Abstract

We demonstrate how the configuration and magnitude of a magnetic field, applied during magnetron sputtering of a NiFe/IrMn bilayer, influence the magnetic properties of the structure, such as hysteresis loop shape, coercivity, and exchange bias. Furthermore, we illustrate that it is possible to create a stepwise hysteresis loop in the sample's region with the highest field gradient. The found features can be used for future sensor applications.

Thermal hysteresis of magnetization in NiFe/IrMn exchange-biased ferromagnet

“…In contrast to a SQUID magnetometer, the MOKE setup allows the adjustment of the magnetic field direction close to the easy axis with an accuracy of ∼1 • . The easy axis was determined from the angle corresponding to the maximum coercivity value, as suggested in a previous study [73]. The effect of diminishing the exchange bias value after thermal cycling at H ∼ −H B was found to be irreversible, that is, any further exposure to the magnetic field or heat treatment in high fields, exceeding the exchange bias value, did not result in the recovery of the initial exchange bias value observed in the same sample before thermal cycling.…”

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“…A study was reported about the effect of the magnitude of the applied magnetic field during the film deposition on the magnetic properties of Co/FeMn bilayers [21]. The effect of the configuration and the magnitude of the magnetic field H, during the elaboration of the samples, on the magnetic properties of magnetron sputtered NiFe/IrMn was recently studied [22]. Earlier, experiments were done concerning the annealing (without the application of a magnetic field) and the magnetic annealing (with the application of a magnetic field) of a set of NiFe/ FeMn bilayers, at a temperature equal to 350°C (higher than the Neel temperature T N of FeMn, T N = 220°C).…”

“…The exchange anisotropy is defined in Section 2. Also, in order to ensure that the magnetic moments of (F) and (AF), at the interface, are parallel and coupled, so that the interaction is strong enough to lead to the exchange anisotropy, some preparation conditions or some post-deposition treatments are required [21][22][23][24][25]. These conditions will be discussed in Section 2.…”

Thin-Film Processing Routes for Combinatorial Materials Investigations—A Review

“…However, process development or phase stability can be studied in libraries with a constant composition where some other type of gradient is imposed on the library. This could include parameters, such as source-substrate distance, gas pressure or composition, magnetic field, or substrate bias (“bias-grading”). − A few of these are discussed below.…”