Exchange bias in epitaxially grown CoO/MgO/Fe/Ag(001)

Abstract

CoO/MgO/Fe/Ag(001) films were grown epitaxially and studied using Magneto-Optic Kerr Effect and X-ray Magnetic Linear Dichroism (XMLD). For thick CoO films we show that both the Fe coercivity and exchange bias exhibit the expected monotonic decrease with increasing MgO thickness. For thin CoO films, however, we find that while the coercivity decreases monotonically, the exchange bias increases initially and then decreases with increasing MgO thickness. By measuring the CoO XMLD as a function of MgO thickness, we show that the unusual behavior of the exchange bias at thinner CoO is due to a transition of the CoO spins from rotatable to frozen spins as the MgO thickness increases.

Investigating Exchange Bias and Coercivity in Fe3O4–γ-Fe2O3 Core–Shell Nanoparticles of Fixed Core Diameter and Variable Shell Thicknesses

“…At 2 K, the exchange bias was observed only at the smallest field-cooled values of 0.5 T, and 1 T whereas at 10 K, it was observed only at 0.5 T. (c) The occurrence of unconventional exchange bias in samples S2 (with a maximum value of 20 Oe) at all temperatures and all field-cooling values. The exchange bias effect appears after field-cooling from room temperature (300 K) which is much lower than both the T c of the shell (which is above 820 K) and the T C of the core (which is around 850 K) [46,47]. (d) The exchange bias in sample S2 has a nonmonotonic behavior with temperature as well as with field-cooling.…”

“…For core–shell nanoparticles with good core–shell contact, less (or no) concentrations of interfacial defects might occur with the absence of interfacial SGCs, leading to a different behavior of exchange bias field and coercivity with temperature and field cooling. It is worth mentioning that the amount of the interfacial SGCs can be experimentally determined using X-ray magnetic circular dichroism (XMCD) [28,46,47]. Another method that was applied to layered FM–AFM structures uses the so-called blocking temperature distribution from magnetic hysteresis loops at several conditions [34,35].…”

Asymmetric Magnetization Reversal Behaviors Driven by Exchange Coupling between All-in-All-out Magnetic Domains and Domain Walls in a Eu2Ir2O7 Single Crystal

“…We now discuss how the intrinsic exchange coupling between AIAO AFM domains and FM DWs could lead to the above asymmetric behaviors. Generally, in the exchange-coupled FM/AFM systems, after the FC procedure, two types of interfacial uncompensated spins named as rotatable and frozen spins exist at the interfaces, as experimentally detected by the X-ray magnetic linear dichroism. , During the isothermal field cycles, the former will rotate with field reversal, the latter as pinning center can generate the EB field. In Eu 2 Ir 2 O 7 , these two types of spins within the DWs (Figure b) can be formed after FC.…”

Benefit of inserting a (Cu/Pt) intermixing dual barrier for the blocking temperature distribution of exchange biased Co/(Cu/Pt)/IrMn stacks

“…Additionally, long range interactions have been modelled and experimentally reported in the literature between a F and an AF, although the spacer did not involve Pt nor a Pt based alloys. [31][32][33][34][35] Finally, we attempted (Pt1/AlOx2/Cu1) trilayer barrier. The total barrier thickness was set to 4 nm so as to compare with the (Pt2/Cu2) dual barrier.…”