Magneto-Optical Reflection Spectroscopy with Linear Polarised Synchrotron Radiation on Monocrystalline Fe, Co, and Ni Thin Films

Die Entwicklung und Erforschung neuer auf magnetischen Materialien basierenden Systeme, z.B. für die Spintronik, schreitet stetig voran. Zur Untersuchung und Charakterisierung solcher magnetischer Materialien haben sich magneto-optische Spektroskopiemethoden mit polarisierter Synchrotronstrahlung fest etabliert. In der vorliegenden Arbeit wurden systematisch die ferromagnetischen Übergangsmetalle Fe, Co und Ni in kristalliner Form mittels magneto-optischer Reflexionsspektroskopie an den 3p- und 2p-Kanten untersucht. Im Gegensatz zur häufig genutzten Elektronenspektroskopie zeigt sich die Reflexionsspektroskopie als photon-in – photon-out Methode vor allem im extremen Ultraviolet (EUV) an den 3p-Kanten als besonders gut geeignet, da das Reflexionsvermögen der Proben in diesem Energiebereich auch für senkrechten Lichteinfall leicht messbar ist. In jüngster Zeit konzentriert sich die Forschung auf die Beeinflussung magnetischer und elektronischer Eigenschaften durch kristalline Anisotropie und deren Detektion mittels magneto-optischer Spektroskopiemethoden. Hierzu existieren bisher nur einige wenige Messungen, hauptsächlich an den 2p-Kanten von Fe-, Co- und Ni-Verbindungen. Das Hauptaugenmerk der Arbeit liegt auf dem Einfluss der magnetokristallinen Anisotropie auf magneto-optische Effekte an den 3p-Kanten von reinem Fe, Co und Ni. Es kann gezeigt werden, dass sich der transversale und der longitudinale magneto-optische Kerr-Effekt (L-MOKE und T-MOKE), welche linear in der Magnetisierung sind, als ungeeignet erweisen die Orientierung der magnetischen Momente im Kristall zu detektieren. In dieser Arbeit steht daher der magnetische Röntgenlineardichroismus (XMLD), welcher quadratisch in der Magnetisierung ist, im Vordergrund. Es konnte hier erstmalig gezeigt werden, dass der XMLD auch an den 3p-Kanten sehr empfindlich auf die Orientierung der Magnetisierung bezüglich der Kristallachsen reagiert. Dabei erfahren die XMLD-Spektren für unterschiedliche Orientierung des Kristalls Änderungen von bis zu 100%. In Kombination mit den Vorteilen der Reflexionsspektroskopie macht dies den XMLD zu einem hervorragenden Werkzeug um magnetische kristalline Strukturen zu untersuchen. Zudem wird gezeigt, dass Interferenzeffekte einen entscheidenden Einfluss auf die mittels Reflexionsspektroskopie gemessenen Spektren haben können. Im Gegensatz zu T-MOKE zeigt sich der XMLD an den 3p-Kanten jedoch wesentlich unanfälliger gegen störende Einflüsse von Interferenz. Zur Detektion des XMLD, der in etwa eine Größenordnung geringer ausfällt als z.B. T-MOKE, wurden im Rahmen dieser Arbeit umfangreiche Experimentiervorrichtungen entwickelt, aufgebaut und in Betrieb genommen. Ein weiterer Schwerpunkt dieser Arbeit ist die Validierung theoretischer Bandstrukturmodelle. Die vorgestellten experimentellen Spektren werden mit ab initio Rechnungen verglichen und es werden Rückschlüsse auf die Anwendbarkeit eines Ein-Elektronen-Ansatzes gezogen. Dabei konnte gezeigt werden, dass ab initio Rechnungen mittels LSDA die XMLD-Spektren an den 3p-Kanten von Fe sehr gut reproduzieren können. Zudem wird ein Modell vorgestellt, welches es erlaubt die Austauschaufspaltung der Rumpfzustände direkt in den XMLD-Spektren zu identifizieren. Die in der Arbeit systematisch durchgeführte Untersuchung des XMLD erweitert somit das Verständnis des magnetischen Röntgenlineardichroismus auf den Energiebereich des EUV und kann als Grundstein für zukünftige Anwendungen dienen, welche diesen Energiebereich nutzen.The development and investigation of new electronic systems based on magnetic materials, e.g. in spintronics, is still in progress. To characterise and explore such magnetic materials the magneto-optical spectroscopies with polarized synchrotron radiation are an established tool. This thesis deals with the systematic exploration of the ferromagnetic transition metals Fe, Co, and Ni at their 3p and 2p edges using reflection spectroscopy. In contrast to the often used total electron yield technique the reflection spectroscopy as a photon-in – photon-out method is appropriate especially in the extreme ultra violet (XUV) at the 3p edges because of the good sample reflectance in this energy range even at normal incidence. Recently, the influence on electronic and magnetic properties by crystalline anisotropy and its detection with magneto optical spectroscopies comes into the focus of research. Up to now only a few measurements exist mainly at the 2p edges of Fe, Co, and Ni alloys. The main part of this thesis deals with the influence of the magnetocrystalline anisotropy on magneto optical effects at the 3p edges of pure Fe, Co, and Ni. It can be shown that the longitudinal and the transversal magneto-optical Kerr effect (L-MOKE and T-MOKE), which are linear in magnetisation, are inapplicable to detect the orientation of the magnetic moments in the crystal. Therefore, this thesis is focused on the x-ray magneitc linear dichroism (XMLD), which is quadratic in magentization. It can be shown for the first time that also at the 3p edge the XMLD is very sensitive to the magnetization orientation within the crystal. The XMLD signal undergoes changes up to 100% when changing the orientation of the crystal. In combination with the advantages of reflection spectroscopy the XMLD turns out as a perfectly suitable tool for the investigation of magnetic crystal structures. Additionally in this thesis it is shown that interference effects can have a drastic impact on the magneto-optical spectra measured in reflection but in contrast to T-MOKE the XMLD at the 3p edges is nearly unaffected by interference effects. To detect the XMLD, which is about one order of magnitude smaller than e.g. T-MOKE, versatile experimental devices have been developed and deployed within the scope of this thesis. A second main aspect of this thesis is the validation of theoretical band structure models. The presented experimental spectra are compared with ab initio calculations and the applicability of an one electron model is discussed. It is shown that with an LSDA approach the XMLD spectra of Fe can be described very well. In addition a simple model is introduced which allows to identify the core level exchange splitting directly within the spectral structures of the XMLD. The systematic investigations of the XMLD at the 3p edges presented in this thesis expands the understanding of the XMLD to the energy range of the XUV and can be used as a foundation for future experiments using this energy range

LiXEdrom: High Energy Resolution RIXS Station dedicated to Liquid Investigation at BESSY II

LiXEdrom is an experimental station dedicated to high resolution RIXS measurements on liquid samples. It is equipped with two VLS gratings and advanced photon detector (MCP/phosphorous screen/CCD), covering soft X-ray range of 200 – 1200 eV. The efficient differential pumping and cooling systems ensure successful executions of X-ray spectroscopy on liquid samples in vacuum. Liquid samples are introduced into the vacuum chamber by micro-jet or flow-cell techniques

Muscle, functional and cognitive adaptations after flywheel resistance training in stroke patients : a pilot randomized controlled trial

Resistance exercise (RE) improves neuromuscular function and physical performance after stroke. Yet, the effects of RE emphasizing eccentric (ECC; lengthening) actions on muscle hypertrophy and cognitive function in stroke patients are currently unknown. Thus, this study explored the effects of ECC-overload RE training on skeletal muscle size and function, and cognitive performance in individuals with stroke. Thirty-two individuals with chronic stroke (≥6 months post-stroke) were randomly assigned into a training group (TG; n = 16) performing ECC-overload flywheel RE of the more-affected lower limb (12 weeks, 2 times/week; 4 sets of 7 maximal closed-chain knee extensions; <2 min of contractile activity per session) or a control group (CG; n = 16), maintaining daily routines. Before and after the intervention, quadriceps femoris volume, maximal force and power for each leg were assessed, and functional and dual task performance, and cognitive functions were measured. Quadriceps femoris volume of the more-affected leg increased by 9.4 % in TG. Muscle power of the more-affected, trained (48.2 %), and the less-affected, untrained limb (28.1 %) increased after training. TG showed enhanced balance (8.9 %), gait performance (10.6 %), dual-task performance, executive functions (working memory, verbal fluency tasks), attention, and speed of information processing. CG showed no changes. ECC-overload flywheel resistance exercise comprising 4 min of contractile activity per week offers a powerful aid to regain muscle mass and function, and functional performance in individuals with stroke. While the current intervention improved cognitive functions, the cause-effect relationship, if any, with the concomitant neuromuscular adaptations remains to be explored. Clinical Trial

Promovierende im Profil: Wege, Strukturen und Rahmenbedingungen von Promotionen in Deutschland ; Ergebnisse aus dem ProFile-Promovierendenpanel

Wer an deutschen Hochschulen promoviert und wie die Wege zur Promotion aussehen, kann seit Jahren nur sehr bedingt beantwortet werden. Das Institut für Forschungsinformation und Qualitätssicherung (iFQ) hat vor diesem Hintergrund drei Studien veröffentlicht, die einen neuen Überblick über das deutsche Promotionswesen geben. Neue Ergebnisse aus dem ProFile-Promovierendenpanel des iFQ geben außerdem erstmals umfassend Aufschluss über die Situation von Promovierenden und die Entwicklungen im Rahmen der strukturierten Promotion. Die Studie "Promovierende im Profil" versammelt neue Einsichten auf der Grundlage einer seit 2009 stattgefundenen Befragung von 28.000 Promovierenden unter Berücksichtigung unterschiedlicher Promotionsmodelle und Fachkulturen

Update breast cancer 2021 part 5 – advanced breast cancer

Despite the COVID 19 pandemic and mostly virtual congresses, innovation in the treatment of breast cancer patients continues at an unabated pace. This review summarises the current developments. Initial overall survival data for CDK4/6 inhibitor treatment in combination with an aromatase inhibitor as the first advanced line of therapy in treatment-naive postmenopausal patients have been published. Similarly, a trial comparing trastuzumab-deruxtecan versus trastuzumab-emtansine revealed a clear benefit regarding progression-free survival. Understanding of biomarkers making checkpoint inhibitor therapy particularly effective is increasing, and new compounds such as oral selective estrogen receptor destabilisers (SERDs) are entering clinical development and completing the first phase III trials

Experienced discrimination amongst European old citizens

This study analyses the experienced age discrimination of old European citizens and the factors related to this discrimination. Differences in experienced discrimination between old citizens of different European countries are explored. Data from the 2008 ESS survey are used. Old age is defined as being 62 years or older. The survey data come from 28 European countries and 14,364 old-age citizens. Their average age is 72 years. Factor analysis is used to construct the core variable ‘experienced discrimination’. The influence of the independent variables on experienced discrimination is analysed using linear regression analysis. About one-quarter of old European citizens sometimes or frequently experience discrimination because of their age. Gender, education, income and belonging to a minority are related to experienced age discrimination. Satisfaction with life and subjective health are strongly associated with experienced age discrimination, as is trust in other people and the seriousness of age discrimination in the country. Large, significant differences in experienced discrimination due to old age exist between European countries. A north-west versus south-east European gradient is found in experienced discrimination due to old age. The socio-cultural context is important in explaining experienced age discrimination in old European citizens. Old-age discrimination is experienced less frequently in countries with social security arrangements. Further research is needed to understand the variation in (old) age discrimination between European countries. Measures recommended include increasing public awareness about the value of ageing for communities and changing public attitudes towards the old in a positive way

Update breast cancer 2021 part 4 – prevention and early stages

This past year has seen new and effective options for further improving treatment outcome in many patients with early-stage breast cancer. Patients with hormone receptor-positive disease benefited significantly from the addition of the CDK4/6 inhibitor abemaciclib to endocrine adjuvant therapy. In triple-negative disease, data were presented for two treatment regimens. Patients with advanced disease (stage 2 and 3) benefit from neoadjuvant treatment with the immune checkpoint inhibitor pembrolizumab in combination with standard chemotherapy, regardless of PD-L1 expression. When neoadjuvant therapy has failed to achieve the desired remission in BRCA1 and BRCA2 mutations, the administration of the PARP inhibitor olaparib has demonstrated an impressive response. Other data address translational issues in HER2-positive breast cancer and neoadjuvant therapy approaches with the oral SERD giredestrant and the PARP inhibitor talazoparib. This review presents and analyses the findings of this yearʼ s most important study outcomes

Update breast cancer 2022 part 4 – advanced-stage breast cancer

For the treatment of patients with advanced HER2-negative hormone receptor-positive breast cancer, several substances have been introduced into practice in recent years. In addition, other drugs are under development. A number of studies have been published over the past year which have shown either an advantage for progression-free survival or for overall survival. This review summarizes the latest results, which have been published at current congresses or in specialist journals, and classifies them in the clinical treatment context. In particular, the importance of therapy with CDK4/6 inhibitors – trastuzumab deruxtecan, sacituzumab govitecan and capivasertib – is discussed. For trastuzumab deruxtecan, an overall survival benefit in HER2-negative breast cancer with low HER2 expression (HER2-low expression) was reported in the Destiny-Breast-04 study. Similarly, there was an overall survival benefit in the FAKTION study with capivasertib. The lack of overall survival benefit for palbociclib in the first line of therapy raises the question of clinical classification

Update Breast Cancer 2022 Part 5 – Early Stage Breast Cancer

The treatment of patients with early stage breast cancer has changed in recent years due to the introduction of pembrolizumab, olaparib, and abemaciclib. These and other drugs with the same class of active ingredient are currently in trial for various indications. This review article summarizes the latest results that have either been presented at major conferences such as the ESMO 2022 or published recently in international journals. This includes reports on newly discovered breast cancer genes, atezolizumab in neoadjuvant therapy in HER2-positive patients, long-term data from the APHINITY study, and on how preoperative peritumoral application of local anesthetics can influence the prognosis. We also present solid data on dynamic Ki-67 from the ADAPT studies