Non-collinear exchange coupling in Fe/Mn/Fe(001): insight from scanning tunneling microscopy

Pierce, Daniel T.; Davies, Angela; Stroscio, Joseph A.; Tulchinsky, D.A.; Unguris, John; Celotta, Robert

doi:10.1016/s0304-8853(00)00551-5

Cited by 28 publications

(41 citation statements)

References 33 publications

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“…The period of the multilayer, being the sum of the individual layer thicknesses, is commonly in the nm range. The magnetic coupling in multilayer systems is shown to be strongly dependent on the layer thickness, the interface quality/roughness [5,6] and the lattice mismatch [7], which in turn can result in magnetic frustration and non collinear coupling [8,9]. The applicability of magnetic materials depends on how much control one has over these features.…”

Section: Magnetic Materialsmentioning

confidence: 99%

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Materials Design from First Principles : stability and magnetism of nanolaminates

Dahlqvist¹

2014

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The front cover image is a close up of M (red and blue spheres) and X (grey sphere) in M 2 AX. In the background its nanolaminated structure consisting of ordered, clustered, and disordered atoms or magnetic moments is illustrated.The spine image shows charge redistribution for an interstitial oxygen atom in Cr 2 AlC where blue indicate gain of electrons and red loss of electrons.The back cover image shows charge redistribution when oxygen substitutes for carbon in Ti 2 AlC where blue indicate gain of electrons and red loss of electrons. My daughter described it as "a planet, with water, and trees, and blue leaves". © Martin Dahlqvist, unless otherwise stated. Printed by LiU-Tryck, Linköping, Sweden, 2014 To my JETs ♥ v ABSTRACT In this thesis, first-principles calculations within density functional theory are presented, with a principal goal to investigate the phase stability of so called M n+1 AX n (MAX) phases. MAX phases are a group of nanolaminated materials comprised of a transition metal (M), a group 12-16 element (A), and carbon or nitrogen (X). They combine ceramic and metallic characteristics, and phase stability studies are motivated by a search for new phases with novel properties, such as magnetism, and for the results to be used as guidance in attempted materials synthesis in the lab.To investigate phase stability of a hypothetical material, a theoretical approach has been developed, where the essential part is to identify the set of most competing phases relative to the material of interest. This approach advance beyond more traditional evaluation of stability, where the energy of formation of the material is generally calculated relative to its single elements, or to a set of ad hoc chosen competing phases. For phase stability predictions to be reliable, validation of previous experimental work is a requirement prior to investigations of new, still hypothetical, materials. It is found that the predictions from the developed theoretical approach are consistent with experimental observations for a large set of MAX phases. The predictive power is thereafter demonstrated for the new phases Nb 2 GeC and Mn 2 GaC, which subsequently have been synthesized as thin films. It should be noted that Mn is used for the first time as sole M-element in a MAX phase. Hence, the theory is successfully used to find new candidates, and to guide experimentalists in their work on novel promising materials. Phase stability is also evaluated for MAX phase alloys. Incorporation of oxygen in different M 2 AlC phases are studied, and the results show that oxygen prefer different sites depending on M-element, through the number of available non-bonding M delectrons. The theory also predicts that oxygen substituting for carbon in Ti 2 AlC stabilizes the material, which explains the experimentally observed 12.5 at% oxygen (x = 0.5) inMagnetism is a recently attained property of MAX phase materials, and a direct result of this Thesis work. We have demonstrated the importance of choice of magnetic spin configuration and elec...

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Section: Magnetic Materialsmentioning

confidence: 99%

“…This is the Hermann-Mauguin notation used to represent symmetry elements in point groups and space groups and it is preferred in crystallography. 8 Another notation is the Schönflies notation which is usually used in spectroscopy.…”

Section: N+1 Ax N (Max) Phasesmentioning

confidence: 99%

Materials Design from First Principles : stability and magnetism of nanolaminates

Dahlqvist¹

2014

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“…Here, we will concentrate on the unique contributions made by SEMPA. In a series of studies by the NIST group, various spacer layer materials were investigated: Cr [96][97][98], Ag [99,100], Au [101,102], and Mn [103,104]. The use of wedged interlayers, Fe whiskers as substrates, and the ability of SEMPA to directly measure the magnetization direction with high spatial resolution revealed many of the details and intricacies of the exchange coupling mechanisms.…”

Section: Exchange Coupled Filmsmentioning

confidence: 99%

“…In the most general case, the magnetic coupling can result in non-collinear alignment, i.e., the magnetization directions are at intermediate angles. This has been studied in detail in the Fe/Mn/Fe system [103,104]. A disadvantage of SEMPA is that coupling strengths cannot be measured directly, since SEMPA cannot be applied in a magnetic field (but see later).…”

Section: Exchange Coupled Filmsmentioning

confidence: 99%

SEMPA Studies of Thin Films, Structures, and Exchange Coupled Layers

Oepen¹,

Hopster²

2005

NanoScience and Technology

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Scanning electron microscopy with polarization analysis (SEMPA) has developed into a powerful technique to study domains in ultrathin films. In this chapter, we discuss from a very general point of view the instrumental aspects of the method. Examples of thin film investigations are given that demonstrate unique features of SEMPA. New solutions around apparent limitations of the technique are presented at the end, i.e., analyzing samples with contaminated surfaces and imaging in external fields. IntroductionIn 1982, triggered by the investigations of the energy dependence of the spinpolarization of secondary electrons (SE), the idea emerged to use this effect in a microscope to image magnetic structures [1,2]. The combination of a conventional Scanning Electron Microscope (SEM) and a spin-polarization analyzer promised the potential of investigating magnetic microstructures with high spatial resolution. In 1984, the first spin-SEM was realized by Koike and coworkers [3], followed less than one year later by a microscope built at NIST [4]. The latter group introduced the abbreviation SEMPA, which stands for Scanning Electron Microscope with Polarization Analysis. We will use both acronyms interchangeably. The next instruments followed in Europe [5,6]. A sketch of SEMPA is given in Fig. 7.1. Due to the low depth of information, ultra-clean surfaces are essential, requiring ultrahigh vacuum (UHV) conditions. Since conventional SEMs usually do not operate in UHV, appropriate UHV-compatible columns (or guns) are rare and expensive. Hooked on is the detector system that consists of an electron optic and a spin-polarization analyzer. The optic has to focus the secondaries into the polarization analyzer. The most important feature of the electron optic is the acceptance angle for SE. It is extremely important that the optic collects electrons emitted in the full 2π solid angle.Several microscopes have been realized [7][8][9][10][11][12][13][14], and a few more have been proposed. Basically, all the systems look very similar. Some have attachments for surface

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“…with two independent coupling constants C þ and C À : Until now this model was successfully used to describe results for Fe/Mn/Fe layered systems [3], but it provides only a poor description of the Fe/Cr/Fe system. Here we present a detailed study of interlayer coupling in Fe(100 ( A)/Cr/Fe(100 ( A) system with wedge-type chromium spacers.…”

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confidence: 99%

Temperature dependence of interlayer coupling in Fe/Cr/Fe wedge samples: static and dynamic studies

Demokritov

Дровосеков

Kholin

et al. 2004

Journal of Magnetism and Magnetic Materials

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Non-collinear exchange coupling in Fe/Mn/Fe(001): insight from scanning tunneling microscopy

Cited by 28 publications

References 33 publications

Materials Design from First Principles : stability and magnetism of nanolaminates

Materials Design from First Principles : stability and magnetism of nanolaminates

SEMPA Studies of Thin Films, Structures, and Exchange Coupled Layers

Temperature dependence of interlayer coupling in Fe/Cr/Fe wedge samples: static and dynamic studies

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