Hard x-ray photoelectron spectroscopy of tunable oxide interfaces

Müller, Martina; Lömker, Patrick; Rosenberger, Paul; Hamed, Mai Hussein; Mueller, David N.; Heinen, R.; Szyjka, Thomas; Baumgarten, L.

doi:10.1116/6.0001491

Cited by 22 publications

(12 citation statements)

References 57 publications

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“…provide invaluable information about the morphology, surface composition and oxidation state, and crystallographic orientation, these techniques are often performed ex situ and operando , which can result in some surface changes due to changing the surface atmosphere of the electrode. However, some methods have been developed to obtain as close to in situ data as possible using ultrahigh vacuum systems but have a focus on surface characterization rather than in situ electron transfer reactions. , In order to gain a full understanding of the electrode surface properties, electroanalytical techniques are needed to elucidate the electron transfer properties. SECM has become a versatile technique used for a number of different systems including corrosion, , electrocatalysis, and photoelectrocatalyis among many others.…”

Section: Discussionmentioning

confidence: 99%

Scanning Electrochemical Microscopy for Chemical Imaging and Understanding Redox Activities of Battery Materials

Strange

Wornyo

et al. 2023

Chemical & Biomedical Imaging

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Improving the charge storage capacity and lifetime and charging/discharging efficiency of battery systems is essential for large-scale applications such as long-term grid storage and long-range automobiles. While there have been substantial improvements over the past decades, further fundamental research would help provide insights into improving the cost effectiveness of such systems. For example, it is critical to understand the redox activities of cathode and anode electrode materials and stability and the formation mechanism and roles of the solid−electrolyte interface (SEI) that forms at the electrode surface upon an external potential bias. The SEI plays a critical role in preventing electrolyte decay while still allowing charges to flow through the system while serving as a charge transfer barrier. While surface analytical techniques such as X-ray photoelectron (XPS), X-ray diffraction (XRD), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and atomic force microscopy (AFM) provide invaluable information on anode chemical composition, crystalline structure, and morphology, they are often performed ex situ, which can induce changes to the SEI layer after it is removed from the electrolyte. While there have been efforts to combine these techniques using pseudo-in situ approaches via vacuum-compatible devices and inert atmosphere chambers connected to glove boxes, there is still a need for true in situ techniques to obtain results with improved accuracy and precision. Scanning electrochemical microscopy (SECM) is an in situ scanning probe technique that can be combined with optical spectroscopy techniques such as Raman and photoluminescence spectroscopy methods to gain insights into the electronic changes of a material as a function of applied bias. This Review will highlight the potential of SECM and recent reports on combining spectroscopic measurements with SECM to gain insights into the SEI layer formation and redox activities of other battery electrode materials. These insights provide invaluable information for improving the performance of charge storage devices.

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Section: Discussionmentioning

confidence: 99%

Scanning Electrochemical Microscopy for Chemical Imaging and Understanding Redox Activities of Battery Materials

Strange

Wornyo

et al. 2023

Chemical & Biomedical Imaging

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“…In the same way as the Co overlayer, a 24 nm thick MgO capping layer was deposited, preventing EuO (and Co) from oxidizing during ex situ handling. [63] Setup: Static magnetic hysteresis measurements were performed in polar (P-MOKE) and longitudinal (L-MOKE) configurations to characterize the magnetic ground state. A positive magnetic field was always used as starting point for the hysteresis.…”

Section: Methodsmentioning

confidence: 99%

Modulation of the Transient Magnetization of an EuO/Co Bilayer Tuned by Optical Excitation

Mönkebüscher

Rosenberger

Mertens

et al. 2023

Adv Materials Inter

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The magnetic proximity effect provides a promising way to increase the low Curie temperature (TC) of europium monoxide (EuO) toward or even above room temperature, while keeping its stoichiometry and insulating properties. This work studies EuO/Co bilayers using static and time‐resolved magneto‐optical Kerr effect measurements, and explores the influence of magnetic proximity on TC and on the spin dynamics in EuO. Excitation above the EuO bandgap results in an ultrafast enhancement of the EuO magnetization followed by a demagnetization within nanoseconds. This behaviour is also visible upon selectively photoexciting Co in the EuO/Co bilayer placed in an out‐of‐plane magnetic field, which is attributed to propagation of a superdiffusive spin current from Co into EuO. As the spin dynamics of Co shows a transient thermal demagnetization, the bilayer provides a system where the transient magneto‐optical signal can be tuned in amplitude and sign by varying external parameters such as the sample temperature or pump fluence. Moreover, in a strong excitation regime it is possible to measure the magnetic hysteresis of the underlying EuO, which is present up to room temperature – giving experimental evidence for the presence of a tuneable magnetic proximity coupling between Co and EuO.

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“…The Fe 2p multiplet structure confirms the formation of stoichiometric Fe 3 O 4 . A more detailed HAXPES investigation of a similar Fe 3 O 4 film grown using the same PLD system was performed in [26][27][28][29].…”

Section: Structural Characterisationmentioning

confidence: 99%

Strain and charge contributions to the magnetoelectric coupling in Fe₃O₄/PMN-PT artificial multiferroic heterostructures

et al. 2022

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The quest to realize new kinds of data storage devices has motivated recent studies in the field of magnetoelectric heterostructures. One of the most commonly investigated systems is Fe3O4/PMN-PT, however, the interplay between different coupling mechanisms is not yet well understood. To disentangle the role of strain and polarisation influence in Fe3O4/PMN-PT, we report on magnetoelectric coupling measurements for different orientations of the applied magnetic field and for two different substrate cuts, PMN-PT(001) and PMN-PT(011). For Fe3O4/PMN-PT(011), having the sample aligned such that the magnetic field is parallel to the [011] easy axis leads to a remanent increase of the magnetisation for each electric field cycle. On the other hand, for the magnetic field along the [100] hard axis, the magnetisation follows a butterfly-like loop characteristic of strain coupling imparted by the substrate. For Fe3O4/PMN-PT(001), the magnetoelectric effect is a superposition of the observed behaviour of both in-plane directions in Fe3O4/PMN-PT(011). The magnetisation shows an initial remanent increase followed by a butterfly like loop. Polarised neutron reflectometry measurements on Fe3O4/PMN-PT(011) shows no difference between the behaviour at the interface and the bulk of the film and no decline of the interaction further away from the shared interface. Our results demonstrate the role of strain and polarisation on the magnetisation of the Fe3O4 layer and provide a clear step towards the design of future magnetoelectric systems.

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Hard x-ray photoelectron spectroscopy of tunable oxide interfaces

Abstract: Note: This paper is a part of the Special Collection Commemorating the Career of Charles S. Fadley.

Cited by 22 publications

References 57 publications

Scanning Electrochemical Microscopy for Chemical Imaging and Understanding Redox Activities of Battery Materials

Scanning Electrochemical Microscopy for Chemical Imaging and Understanding Redox Activities of Battery Materials

Modulation of the Transient Magnetization of an EuO/Co Bilayer Tuned by Optical Excitation

Strain and charge contributions to the magnetoelectric coupling in Fe₃O₄/PMN-PT artificial multiferroic heterostructures

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Hard x-ray photoelectron spectroscopy of tunable oxide interfaces

Abstract: Note: This paper is a part of the Special Collection Commemorating the Career of Charles S. Fadley.

Cited by 22 publications

References 57 publications

Scanning Electrochemical Microscopy for Chemical Imaging and Understanding Redox Activities of Battery Materials

Scanning Electrochemical Microscopy for Chemical Imaging and Understanding Redox Activities of Battery Materials

Modulation of the Transient Magnetization of an EuO/Co Bilayer Tuned by Optical Excitation

Strain and charge contributions to the magnetoelectric coupling in Fe3O4/PMN-PT artificial multiferroic heterostructures

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Product

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Strain and charge contributions to the magnetoelectric coupling in Fe₃O₄/PMN-PT artificial multiferroic heterostructures