Antiferromagnetic interlayer exchange coupling in all-semiconductingEuS∕PbS∕EuStrilayers

Abstract

Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. A comprehensive experimental study on the antiferromagnetic interlayer exchange coupling in high quality epitaxial all-semiconducting EuS/ PbS/ EuS trilayers is reported. The influence of substrates, of the thickness of the nonmagnetic PbS spacer layer, and of temperature was investigated by means of SQUID magnetometry. In trilayers with a PbS thickness between 4 and 12 Å the low temperature hysteresis loops showed the signature of antiferromagnetic coupling. The value of the interlayer exchange coupling energy was determined by simulating the data based on a Stoner-Wohlfarth model. An important observation was that the interlayer exchange coupling energy varies strongly with temperature, consistent with a power-law dependence of the exchange coupling constant on the saturation magnetization of the EuS layers. While no theoretical description is readily available, we conjecture that the observed behavior is due to a dependence of the interlayer exchange coupling energy on the exchange splitting of the EuS bands.

Magnetic Properties of EuS/Co Multilayers on KCl and BaF₂ Substrates

“…at temperature close to the Curie temperature of bulk EuS. Such behavior was already observed in the case of previously studied magnetically coupled EuS/PbS [9,10] and EuS/SrS [11] multilayers and can be interpreted as a result of antiferromagnetic alignment of magnetization vectors of Co and EuS layers. Figure 3 shows the results of the measurements of the temperature dependence of magnetization M (T ) carried out for EuS/Co/EuS trilayer.…”

“…Additionally, interlayer coupling J between the magnetic layers is taken into account. Thus, the total magnetic areal energy density E/A of the model exchange coupled bilayer system can be expressed as [9]:…”

“…Since the Stoner-Wohlfarth model generally overestimates coercivities, we chose to simulate the unhysteretic M (H) curves, obtained in the calculations of global minimum of the total energy. By fitting the low-field behavior, the interlayer exchange coupling energy J (proportional to the magnetic field switching from antiferromagnetic to ferromagnetic configuration) and the crystalline anisotropy constants K 1,2 (influencing mainly the slope of the plateau) can be determined [9]. As a result of such modeling procedure the antiferromagnetic interlayer exchange coupling between EuS and Co layers was found for EuS/Co/EuS//KCl trilayer with simulated values of the interlayer exchange coupling energy J of the order of −0.1 mJ/m 2 , and cubic anisotropy constants K 1 = 30 kJ/m 3 and K 2 = 90 kJ/m 3 of EuS and Co layers, respectively.…”

Magnetic Properties of EuS-SrS Semiconductor Multilayer Structures

“…We consider the case of multilayers with relatively thick SrS nonmagnetic spacer (45Å and thicker) to deal with the system of ferromagnetic EuS layers magnetically decoupled from each other. The effect of antiferromagnetic interlayer coupling between EuS layers via nonmagnetic spacer, discovered in closely related in EuS-PbS multilayers with PbS spacer [3][4][5][6], was also found in EuS-SrS multilayers with ultrathin SrS spacer layer (below 10Å). The EuS-SrS multilayers with ultrathin spacer exhibiting interlayer exchange effects will be discussed in other publication.…”

“…This interpretation is supported by the X-ray diffraction observation that the EuS layer lattice parameter along the normal to the substrate plane is larger than in bulk EuS crystals. Also other basic ferromagnetic parameters of EuS-SrS multilayers, such as magnetic saturation field, coercive field, and in-plane magnetic anisotropy constant are typical of other EuS-based multilayers [4]. Due to very large demagnetization field H D expected in EuS layers (H D = 4πM ≈ 15 kOe at T = 0 K) the dipolar (shape) anisotropy is the dominant anisotropy mechanism in EuS-SrS multilayers with a negligible role of magnetocrystalline anisotropy.…”