Short period oscillation of the interlayer exchange coupling in the ferromagnetic regime in Co/Cu/Co(100)

Abstract

A unique sample was prepared on a Cu(100) single crystal, consisting of three Co layers separated by two Cu layers in the form of wedges oriented perpendicular to each other: Cu(100)/80 Å Co/Cu wedge A/30 Å Co/Cu wedge B/30 Å Co/7 Å Cu/30 Å Au. Position-sensitive magneto-optical Kerr effect measurements along Cu wedge B, at a fixed position on Cu wedge A corresponding to maximum antiferromagnetic (AF) coupling, enabled us to investigate not only the AF but also the ferromagnetic (F) coupling between the two 30 Å Co layers as a function of the Cu thickness. The measurements confirmed both long and short period coupling oscillations in the AF regime, and revealed the predicted extension of the short period through the F regime.

First-principles studies of modulated Co/Cu superlattices with strongly and weakly exchange-biased Co-monolayers

“…The coupling j has the correct order of magnitude (except of the case n = 4) when compared with experimental results on similar systems (e.g. [7]). This means that the exchange-biasing slab Cu 2 Co (1) Cu 2 influences the coupling j (between Co (2) and Co (3) via Cu n ) and reduces it in a substantial way, since in our previous studies with no biasing slab the exchange coupling in CoCu n multilayers was roughly 10 times larger than the present j-value (see [8,5] and comments therein).…”

“…The purpose of the present letter is, to study by reliable ab-initio-calculations the question, to which extent it would be possible to replace the exchange-biasing unit AF in the abovementioned conventional "spin valve system" by a trilayer f erromagnet1/spacer/f erromagnet2 involving e.g. only ferromagnetic Co planes, and Cu as spacer, provided the thickness of the spacer is chosen such as to ensure strong antiferromagnetic coupling of the two ferromagnetic layers [10].…”

“…Systems of this type are not only interesting for fundamental aspects but may also be applied in future magnetic recording devices. It is possible to replace an exchange-biasing antiferromagnet by a trilayer, AF −→ f erromagnet1/spacer/f erromagnet2, provided the thickness of the spacer is chosen such as to ensure strong antiferromagnetic coupling of the two ferromagnetic layers [7]. In an attempt to get more insight into the nature of exchange coupling and possible magnetic phases which may appear, we have studied systematically by the spin-polarized ab initio LMTO-ASA method (linearized muffin-tin orbitals, atomic sphere approximation, scalarrelativistic version, see [5]) the series of multilayers with supercell Cu 2 Co (2) Cu 2 Co (1) Cu 2 Co (2) Cu n Co (3) Cu n of the (001) face-centred tetragonal structure (i.e.…”

Manifold domain structure of double films with perpendicular magnetic anisotropy

“…Nevertheless, the minor M-H loop, see dashed line in figure 1(a), done after saturating the sample in a positive H and applying a negative field of -185 Oe, shows a marginal shift, ≈ 10 Oe, suggesting a small value of a bilinear exchange coupling, as could be expected for structures with interleaving copper layers larger than 3 nm [15]. The in-plane M-H loops does not show anomalies related to the plateaus observed in the hysteresis loops taken with H perpendicular to the plane [see figure 1…”

Intensity enhancement of ferromagnetic resonance modes in exchange coupled magnetic multilayers

“…Unless otherwise specified, the physical parameters used in this section are given in table 1. = J 0.2 eff mJ m −2 is a typical value for pairs of magnetic layers with Cu or Ru separators ∼1-2 nm thick [65][66][67][68][69]. It is chosen to be the same at all interfaces for easier interpretation and exploration of the different contributions to the intensity of the resonance modes.…”