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Interpretation Bias in the Context of Depressed Mood: Assessment Strategies and the Role of Self-Generation in Cognitive Bias Modification: Interpretation Bias in the Context of Depressed Mood:Assessment Strategies and the Role of Self-Generation in Cognitive Bias Modification
Get PDFNegatively biased interpretation has been hypothesized as an important factor in the aetiology and maintenance of depression. Recently developed cognitive bias modification paradigms, intending to change these biases towards a more optimistic interpretation tendency (CBM-I), seem to offer new promising implications for cognitive therapy innovation. Surprisingly, the increasing interest in the modifiability of interpretation bias is contrasted by a severe lack of methodological and measurement development studies. A review of current research revealed 1) a severe lack of psychometrically evaluated measures for depressionrelated interpretation bias and its modification, 2) inconsistent findings for the existence of depression-related interpretation bias depending on the (direct or indirect) assessment paradigm, 3) a demand for profound knowledge about the underlying work mechanisms and best ingredients for CBM-I procedures, and 4) a lack of measures and CBM-I training materials in the German language.
With these considerations in mind, the objectives of this dissertation were 1) to develop and evaluate an internally consistent and valid measure for the assessment of depression-related interpretation bias and its modification, 2) to validate an indirect priming task to assess interpretation bias and to further examine the interrelations of four different direct and indirect assessment paradigms, 3) to evaluate a new and more active CBM-I variant and test its effectiveness in comparison with guided CBM-I and a control group, and 4) to provide valid test and CBM-I training materials in German.
The aim of study 1 was to develop and evaluate a pragmatic assessment instrument, consisting of a 30-item questionnaire (long version) and two 15-item parallel short versions (A and B). Items were generated as ambiguous sentences, reflecting three relevant content areas based on Beck’s cognitive triad (Beck et al., 1979). All three versions of the instrument were found to be structurally stable, internally consistent and valid. In line with Beck’s cognitive triad (Beck et al., 1979) in depression, confirmatory factor analyses determined a three factor solution (self, experiences, future). Significant correlations were found between all scales and depressive mood. The two short versions represent the same underlying constructs, share identical psychometric properties and possess high parallel-test reliability. The study was the first to evaluate and confirm the factorial validity as well as the parallel-test reliability, and therefore suitability to measure modification of interpretation bias measure in the context of depressed mood.
The aim of study 2 was to evaluate an indirect affective priming task using homophones as ambiguous material and to compare this task to three different already established interpretation bias paradigms, namely an ambiguous scenarios test, a scrambled sentences test under cognitive load, as well as a homophone paradigm. No empirical support for mood-related interpretation bias was found for the newly developed affective priming task as well as the homophone task, which both did not differentiate between dysphoric and non-dysphoric individuals. The ambiguous scenarios test and the scrambled sentences test under cognitive load were shown to be internally consistent and valid instruments that were also highly intercorrelated. These findings emphasize the challenge to create valid ambiguous test stimuli for the measure of depression-related interpretation bias as well as the inequality of different assessment paradigms. Study 2 was the first study to examine the relatedness of four different direct and indirect assessment paradigms for the measure of depression-related interpretation bias in one sample.
The aim of study 3 was to compare the efficacy of CBM-I requiring participants to imagine standardized positive resolutions to a novel, more active training version that required participants to generate the positive interpretations themselves. Participants were randomly allocated to (1) standardized CBM-I, (2) self-generation CBM-I or (3) a control group. Outcome measures included self-report mood measures and a depression-related interpretation bias measure. Both positive training variants significantly increased the tendency to interpret fresh ambiguous material in an optimistic manner. However, only the standardized imagery CBM-I paradigm positively influenced mood. Study 3 successfully evaluated a new CBM-I variant, gained insights about the role of self-generation and added further support to the potential therapeutic significance of imagery-based cognitive bias modification strategies. Altogether, this dissertation significantly contributed to the research field of depressionrelated interpretation bias by 1) filling a gap in measure development studies, 2) increasing the knowledge of the relatedness of different assessment paradigms, 3) increasing the knowledge about the working mechanisms and optimal ingredients of successful CBM-I, and 4) evaluating and providing assessment as well as CBM-I training materials for the German language context.Ein negativer Interpretationsbias bezieht sich auf die Tendenz, mehrdeutige Reize (z.B. Situationen, Gesichtsausdrücke, Rückmeldung von anderen Personen) in einer pessimistischen Art und Weise zu interpretieren. Diese kognitive Verzerrung im Rahmen der Informationsverarbeitung wird als wichtiger Faktor für die Entstehung und Aufrechterhaltung von depressiven Störungen diskutiert. Insbesondere die Modifikation dieser Tendenz zu einem positiveren Interpretationsstil (Cognitive bias modification targeting interpretation; CBM-I) erweckte in den vergangenen Jahren großes Forschungsinteresse, da diese innovativen, computergestützten Techniken wirkungsvolle Behandlungsansätze für die Therapie von Depressionen bedeuten könnten.
Nach aktuellem Forschungsstand besteht jedoch 1.) ein Mangel an hinreichend evaluierten Instrumenten für die Erhebung von depressionsbedingten Interpretationsverzerrungen und insbesondere deren Veränderbarkeit, 2.) eine inkonsistente Befundlage für die Existenz von depressionsbedingten Interpretationsverzerrungen in Abhängigkeit von der (direkten oder indirekten) Erhebungsmethode, 3.) ein Bedarf an genaueren Erkenntnissen über die zugrunde liegenden Wirkmechanismen und effektivsten Komponenten von CBM-I und 4.) ein Fehlen von CBM-I Materialien und Erhebungsmethoden in deutscher Sprache. Vor diesem Hintergrund wurden die Ziele dieser Dissertation formuliert, die neben einer kurzen Einführung in das Themengebiet und einer abschließenden Diskussion aus drei Studien besteht.
Das Ziel der ersten Studie war die Entwicklung und Validierung eines pragmatischen Erhebungsinstrumentes zur Messung von depressionsbedingten Interpretationsverzerrungen, bestehend aus einem Fragebogen (Langfassung, 30 Items) und zwei Kurz- bzw. Parallelversionen (A und B, jeweils 15 Items). In den Items werden emotional mehrdeutig interpretierbare Szenarien beschrieben, deren Inhalte Beck‘s kognitive Triade (Beck et al., 1979) widerspiegeln. Den Ergebnissen zufolge können alle drei Versionen des Instruments als strukturell stabil, internal konsistent und valide bewertet werden. In Übereinstimmung mit der Theorie der kognitiven Triade (Beck et al., 1979) wurde mittels konfirmatorischer Faktorenanalyse eine Dreifaktorenlösung (Selbst, Erfahrungen, Zukunft) festgestellt. Signifikante Korrelationen wurden zwischen allen Skalenwerten und depressiver Symptomatik gefunden. Die beiden Parallelversionen weisen ähnliche psychometrische Eigenschaften sowie eine hohe Paralleltest-Konsistenz auf.
Das Ziel der zweiten Studie war die Validierung eines indirekten, affektiven Priming- Verfahrens, in dem homophone Wörter als emotional zweideutige Stimuli eingesetzt wurden. Dieser Test wurde zusätzlich mit drei bereits etablierten Erhebungsparadigmen (Ambiguous Scenarios Test; Scrambled Sentences Test, Homophone-Test) verglichen. Hinsichtlich der Ergebnisse konnte keine empirische Unterstützung für den affektiven Priming-Test sowie für den Homophone-Test gefunden werden; beide Tests zeigten keinen Zusammenhang mit depressiven Symptomen. Der Ambiguous Scenarios Test und der Scrambled Sentences Test erwiesen sich als internal konsistent und valide und wiesen außerdem eine hohe Interkorrelation auf. Die Ergebnisse geben Aufschluss über die Vergleichbarkeit der unterschiedlichen Erhebungsparadigmen.
Das Ziel der dritten Studie war die Entwicklung und Evaluation einer neuen, aktiveren CBM-I Variante, in der die Teilnehmer mittels eines computergestützten Trainings aufgefordert wurden, positive Interpretationen auf emotional mehrdeutige Szenarien eigenständig zu generieren. Die Ergebnisse der neuen CBM-I-Variante wurden mit den Ergebnissen einer herkömmlichen CBM-I-Variante (Standard-CBM-I) sowie den Ergebnissen einer Kontrollgruppe verglichen. Es zeigte sich, dass sowohl die neue CBM-I-Variante als auch Standard-CBM-I die Interpretationstendenz signifikant in eine positive Richtung verbesserten. Darüber hinaus konnte durch Standard-CBM-I eine stimmungsaufhellende Wirkung erzielt werden
Development of Lithium Ion Battery Dynamic Model: Development of Lithium Ion BatteryDynamic Model
Get PDFThe increased popularity of electric vehicles and e-mobility among the people, have encouraged many automotive companies and research organisations to develop good strategies for drivetrain designs involving batteries. As seen in the department of Alternative Powertrains research is carried out on hybrid fuel cell and electric vehicles. This thesis deals with the development of lithium ion battery model for electric vehicle simulations. A novel approach using black box modelling is developed for development of battery model using only the available battery measurements. Furthermore, a measurement test strategy is formulated providing the process direction and measurement parameters to be considered. Developed battery model provide voltage estimates for given Charge rate,temperature and State of Charge (SOC). The comparison of experimentally obtained and model estimated values. The model developed has a very good accuracy in estimation
Ein Beitrag zur Verbesserung der Eigenschaften magnetisch-induktiver Tastspulen
Get PDFMagnetisch-induktive Techniken finden seit langer Zeit viele Anwendungsfelder in der Medizin, Sicherheitstechnik und der Industrie. Obwohl die technischen Grundlagen seit vielen Jahrzehnten bekannt sind, werden auf Basis detaillierter Analysen spezielle Lösungsansätze verfolgt, die neuartiges Anwendungspotential erschließen sollen. Dazu dienen verbesserte Werkzeuge wie Computersimulationen und analytische Berechnungen sowie neu kombinierte Methoden und Aufbauten aus Leistungselektronik und Signaldetektion.
Die Vorteile magnetisch-induktiver Techniken sind dabei u.a., dass sie das Prüfobjekt nicht schädigen, berührungslos arbeiten, robust gegenüber Verschmutzungen und einfach im Aufbau sind. Ein Nachteil dieser Technik ist die unzureichende Auflösung von feinen Strukturen.
In der aktuellen Forschung und Entwicklung werden unterschiedliche Spulenanordnungen zur Anwendung in industriellen und medizinischen Fragestellungen untersucht und optimiert. Thema dieser Arbeit ist es, durch Verbesserung der Spuleneigenschaften, neue Anwendungsbereiche für die zerstörungsfreie Materialprüfung zu erschließen. Es wird eine Methode vorgestellt, die Eigenschaften magnetisch-induktiver Tastspulen zu verbessern und so den Aufwand bei der Signalverarbeitung zur Rekonstruktion im Rechner zu reduzieren sowie die Auflösung zu erhöhen. Dazu werden zwei Spulenanordnungen, Transmissions - Tastspulen und Gradiometer - Tastspulen, vergleichend gegenübergestellt und ihre technischen Grenzen aufgezeigt.Magneto-inductive techniques are found in many fields of application areas so in medicine, security technology and industry. Although the technical basis has been known for many decades, special solutions are pursued on the basis of detailed analysis that should open new application potential. These are enhanced tools such as computer simulations, analytical calculations, new combined methods and structures of power electronics and signal detection.
The advantages of magneto-inductive techniques are that they do not damage the test object, are contactless, robust against dirt and simple in construction. A disadvantage of this technique is the insufficient resolution of fine structures.
In current research and development different coil assemblies are investigated in industrial and medical applications. The aim of this work is to improve the coil properties by changing geometric constructions and current patterns of the coils, in order to allow a sharper localization of objects in space and to tap new application areas for non-destructive testing. A method to improve the properties of magneto-inductive coils and thus to reduce the effort in signal processing and image reconstruction as well as to increase the resolution is presented. Two different coil assemblies, gradiometer – coils and transmission – coils, are compared and their technical limits shown
Symmetric Fractional Diffusion and Entropy Production
Get PDFThe discovery of the entropy production paradox (Hoffmann et al., 1998) raised basic questions about the nature of irreversibility in the regime between diffusion and waves. First studied in the form of spatial movements of moments of H functions, pseudo propagation is the pre-limit propagation-like movements of skewed probability density function (PDFs) in the domain between the wave and diffusion equations that goes over to classical partial differential equation propagation of characteristics in the wave limit. Many of the strange properties that occur in this extraordinary regime were thought to be connected in some manner to this form of proto-movement. This paper eliminates pseudo propagation by employing a similar evolution equation that imposes spatial unimodal symmetry on evolving PDFs. Contrary to initial expectations, familiar peculiarities emerge despite the imposed symmetry, but they have a distinct character
Balancing of Network Energy using Observer Approach
Get PDFEfficient energy use is primarily for any sensor networks to function for a longer time period. There have been many efficient schemes with various progress levels proposed by many researchers. Yet, there still more improvements are needed. This thesis is an attempt to make wireless sensor networks with further efficient on energy usage in the network with respect to rate of delivery of the messages.
In sensor network architecture radio, sensing and actuators have influence over the power consumption in the entire network. While listening as well as transmitting, energy is consumed by the radio. However, if by reducing listening times or by reducing the number of messages transmitting would reduce the energy consumption. But, in real time scenario with critical information sensing network leads to information loss. To overcome this an adaptive routing technique should be considered. So, that it focuses on saving energy in a much more sophisticated way without reducing the performance of the sensing network transmitting and receiving functionalities.
This thesis tackles on parts of the energy efficiency problem in a wireless sensor network and improving delivery rate of messages. To achieve this a routing technique is proposed. In this method, switching between two routing paths are considered and the switching decision taken by the server based on messages delivered comparative previous time intervals. The goal is to get maximum network life time without degrading the number of messages at the server. In this work some conventional routing methods are considered for implementing an approach. This approach is by implementing a shortest path, Gradient based energy routing algorithm and an observer component to control switching between paths. Further, controlled switching done by observer compared to normal initial switch rule. Evaluations are done in a simulation environment and results show improvement in network lifetime in a much more balanced way
All-inkjet-printed thin-film transistors: manufacturing process reliability by root cause analysis
Get PDFWe report on the detailed electrical investigation of all-inkjet-printed thin-film transistor (TFT) arrays focusing on TFT failures and their origins. The TFT arrays were manufactured on flexible polymer substrates in ambient condition without the need for cleanroom environment or inert atmosphere and at a maximum temperature of 150 °C. Alternative manufacturing processes for electronic devices such as inkjet printing suffer from lower accuracy compared to traditional microelectronic manufacturing methods. Furthermore, usually printing methods do not allow the manufacturing of electronic devices with high yield (high number of functional devices). In general, the manufacturing yield is much lower compared to the established conventional manufacturing methods based on lithography. Thus, the focus of this contribution is set on a comprehensive analysis of defective TFTs printed by inkjet technology. Based on root cause analysis, we present the defects by developing failure categories and discuss the reasons for the defects. This procedure identifies failure origins and allows the optimization of the manufacturing resulting finally to a yield improvement
Jahresbericht 2015 / Universitätsbibliothek Chemnitz
Get PDFJahresbericht der Universitätsbibliothek Chemnitz und des Universitätsarchivs- Berichtsjahr 2015Annual report of the University Library of Chemnitz and the University Archive in 201
Plantar sensory vibration thresholds are not influenced by body position
Get PDFMonitoring skin sensitivity is studied to clarify its relationship on balance. Measuring skin sensitivity is performed when subjects are sitting or lying, whereas balance tests are measured during standing. However, afferent signal processing and subsequent efferent responses can be altered by different body positions. Therefore, this study investigated whether vibration perception thresholds (VPTs) are influenced by body positions. Sixty-six healthy subjects (41♀; 25♂) participated in this study. Five measurements of VPTs were performed at each of the three analyzed anatomical locations (heel, first metatarsal head, hallux) of the right plantar foot under two randomized conditions: during sitting and standing. The contact force applied to the probe was measured and controlled within the five trials. Contact forces between the probe and the foot were higher during standing. However, no differences in VPTs were found between conditions. This indicates that VPTs are not different during standing compared to sitting, contrary to our expectations. We conclude that higher forces did not induce increased receptor activity. Since no differences were found between thresholds, future clinical studies can implement plantar VPT tests during sitting in association with balance tests during standing
Resistive switching in BiFeO3-based thin films and reconfigurable logic applications
Get PDFThe downscaling of transistors is assumed to come to an end within the next years, and the semiconductor nonvolatile memories are facing the same physical downscaling challenge. Therefore, it is necessary to consider new computing paradigms and new memory concepts. Resistive switching devices (also referred to as memristive switches) are two-terminal passive device, which offer a nonvolatile switching behavior by applying short bias pulses. They have been considered as one of the most promising candidates for next generation memory and nonvolatile logic applications. They provide the possibility to carry out the information processing and storage simultaneously using the same resistive switching device.
This dissertation focuses on the fabrication and characterization of BiFeO3 (BFO)-based metal-insulator-metal (MIM) devices in order to exploit the potential applications in nonvolatile memory and nonvolatile reconfigurable logics. Electroforming-free bipolar resistive switching was observed in MIM structures with BFO single layer thin film. The resistive switching mechanism is understood by a model of a tunable bottom Schottky barrier. The oxygen vacancies act as the mobile donors which can be redistributed under the writing bias to change the bottom Schottky barrier height and consequently change the resistance of the MIM structures. The Ti atoms diffusing from the bottom electrode act as the fixed donors which can effectively trap and release oxygen vacancies and consequently stabilize the resistive switching characteristics. The resistive switching behavior can be engineered by Ti implantation of the bottom electrodes.
MIM structures with BiFeO3/Ti:BiFeO3 (BFO/BFTO) bilayer thin films show nonvolatile resistive switching behavior in both positive and negative bias range without electroforming process. The resistance state of BFO/BFTO bilayer structures depends not only on the writing bias, but also on the polarity of reading bias. For reconfigurable logic applications, the polarity of the reading bias can be used as an additional logic variable, which makes it feasible to program and store all 16 Boolean logic functions simultaneously into the same single cell of BFO/BFTO bilayer MIM structure in three logic cycles.Die Herunterskalierung von Transistoren für die Informationsverarbeitung in der Halbleiterindustrie wird in den nächsten Jahren zu einem Ende kommen. Auch die Herunterskalierung von nichtflüchtigen Speichern für die Informationsspeicherung sieht ähnlichen Herausforderungen entgegen. Es ist daher notwendig, neue IT-Paradigmen und neue Speicherkonzepte zu entwickeln. Das Widerstandsschaltbauelement ist ein elektrisches passives Bauelement, in dem ein der Widerstand mittels elektrischer Spannungspulse geändert wird. Solche Widerstandsschaltbauelemente zählen zu den aussichtsreichsten Kandidaten für die nächste Generation von nichtflüchtigen Speichern sowie für eine rekonfigurierbare Logik. Sie bieten die Möglichkeit zur gleichzeitigen Informationsverarbeitung und -speicherung.
Der Fokus der vorliegenden Arbeit liegt bei der Herstellung und der Charakterisierung von BiFeO 3 (BFO)-basierenden Metal-insulator-Metall (MIM) Strukturen, um zukünftig deren Anwendung in nichtflüchtigen Speichern und in rekonfigurierbaren Logikschaltungen zu ermöglichen. Das Widerstandsschalten wurde in MIM-Strukturen mit einer BFO-Einzelschicht untersucht. Ein besonderes Merkmal von BFO-basierten MIM-Strukturen ist es, dass keine elektrische Formierung notwendig ist. Der Widerstandsschaltmechnismus wird durch das Modell einer variierten Schottky-Barriere erklärt. Dabei dienen Sauerstoff-Vakanzen im BFO als beweglichen Donatoren, die unter der Wirkung eines elektrischen Schreibspannungspulses nichtflüchtig umverteilt werden und die Schottky-Barriere des Bottom-Metallkontaktes ändern. Dabei spielen die während der Herstellung von BFO substitutionell eingebaute Ti-Donatoren in der Nähe des Bottom-Metallkontaktes eine wesentliche Rolle. Die Ti-Donatoren fangen Sauerstoff-Vakanzen beim Anlegen eines positiven elektrischen Schreibspannungspulses ein oder lassen diese beim Anlegen eines negativen elektrischen Schreibspannungspules wieder frei. Es wurde gezeigt, dass die Ti-Donatoren auch durch Ti-Implantation der Bottom-Elektrode in das System eingebracht werden können.
MIM-Strukturen mit BiFeO 3 /Ti:BiFeO 3 (BFO/BFTO) Zweischichten weisen substitutionell eingebaute Ti-Donatoren sowohl nahe der Bottom-Elektrode als auch nahe der Top-Elektrode auf. Sie zeigen nichtflüchtiges, komplementäres Widerstandsschalten mit einer komplementär variierbaren Schottky-Barriere an der Bottom-Elektrode und an der Top-Elektrode ohne elektrische Formierung. Der Widerstand der BFO/BFTO-MIM-Strukturen hängt nicht nur von der Schreibspannung, sondern auch von der Polarität der Lesespannung ab. Für die rekonfigurierbaren logischen Anwendungen kann die Polarität der Lesespannung als zusätzliche Logikvariable verwendet werden. Damit gelingt die Programmierung und Speicherung aller 16 Booleschen Logik-Funktionen mit drei logischen Zyklen in dieselbe BFTO/BFO MIM-Struktur
Ferromagnet-Free Magnetoelectric Thin Film Elements
Get PDFThe work presented in this thesis encompasses the design, development, realization and testing of novel magnetoelectric thin film elements that do not rely on ferromagnets, but are based entirely on magnetoelectric antiferromagnets such as Cr2O3. Thin film spintronic elements, and in particular magnetoelectric transducers, are crucial building blocks of high efficiency data processing schemes that could complement conventional electronic data processing in the future. Recent developments in magnetoelectrics have revealed, that exchange biased systems are ill-suited to electric field induced switching of magnetization due to the strong coupling of their ferromagnetic layer to magnetic fields. Therefore, ferromagnet-free magnetoelectric elements are proposed here in an effort to mitigate the practical problems associated with existing exchange biased magnetoelectric elements.
This goal is achieved by establishing an all-electric read-out method for the antiferromagnetic order parameter of thin films, which allows to omit the ferromagnet from conventional exchange biased magnetoelectric elements. The resulting ferromagnet-free magnetoelectric elements show greatly reduced writing thresholds, enabled operation at room temperature and do not require a pulsed magnetic field, all of which is in contrast to state-of-the-art exchange biased magnetoelectric systems.
The novel all-electric read-out method of the magnetic field-invariant magnetization of antiferromagnets, so-called spinning-current anomalous Hall magnetometry, can be widely employed in other areas of thin film magnetism. Its high precision and its sensitivity to previously invisible phenomena make it a promising tool for various aspects of thin solid films. Based on this technique, a deep understanding could be generated as to what physical mechanisms drive the antiferromagnetic ordering in thin films of magnetoelectric antiferromagnets. As spinning-current anomalous Hall magnetometry is an integral probe of the magnetic properties in thin films, it offers no intrinsic scale sensitivity. In order to harness its great precision for scale related information, a statistical framework was developed, which links macroscopic measurements with microscopic properties such as the antiferromagnetic domain size.:TABLE OF CONTENTS
Abbreviations 9
1 Introduction 11
1.1 Motivation 11
1.2 Objectives 12
1.3 Organization of the thesis 13
2 Background 15
2.1 History of magnetoelectric coupling 15
2.2 Long range magnetic ordering 16
2.2.1 Magnetic order parameter and field susceptibility 17
2.2.2 Magnetic proximity effect 19
2.2.3 Exchange bias 20
2.3 Phenomenology of magnetoelectric coupling 21
2.3.1 The linear magnetoelectric effect 21
2.3.2 Magnetoelectric pressure on the antiferromagnetic order parameter 22
2.3.3 Switching the antiferromagnetic order parameter 23
2.4 Realized magnetoelectric thin film elements 24
2.4.1 BiFeO3/CoFe system 24
2.4.2 Cr2O3/Co/Pt system 25
3 Experimental methods 27
3.1 Development of ferromagnet free magnetoelectric elements 28
3.1.1 The substrate 29
3.1.2 The Cr2O3 bulk and top surface 31
3.1.3 The V2O3 or Pt bottom electrodes 33
3.1.4 Epitaxial relationships 34
3.1.5 The Cr2O3 bottom interface 39
3.1.6 Twinning of Cr2O3 39
3.1.7 Hall crosses and patterning processes 43
3.2 Magnetotransport measurements 44
3.2.1 Hall effects 45
3.2.2 Anomalous Hall effect 46
3.2.3 Magnetoelectric writing 47
3.2.4 All electric read out 49
3.3 The experimental setup 50
3.3.1 Temperature control 50
3.3.2 Magnetic field control 51
4 Spinning-current anomalous Hall magnetometry 53
4.1 Characteristics of the technique 53
4.1.1 Operational principle 53
4.1.2 Advantages 55
4.1.3 Magnetic hysteresis loops and field-invariant magnetization 55
4.1.4 Measurement of field-invariant magnetization 56
4.1.5 Limitations 58
4.2 Application of SCAHM to Cr2O3(0001) thin films 59
4.2.1 Criticality and distribution of the antiferromagnetic phase transition 61
4.2.2 Evaluation of the magnetic proximity effect 64
4.3 SCAHM with thin metallic antiferromagnetic IrMn films 65
4.3.1 [Pt/Co]4/IrMn exchange bias system 65
4.3.2 Isolated antiferromagnetic IrMn thin films 67
5 Magnetoelectric performance 69
5.1 Magnetoelectric field cooling 69
5.2 The gate bias voltage 71
5.3 Isothermal binary magnetoelectric writing in Cr2O3 72
6 Order parameter selection in magnetoelectric antiferromagnets 77
6.1 Uncompensated magnetic moment 77
6.2 Extrinsic causes for broken sublattice equivalence 81
6.3 The V2O3 gate electrode 83
7 Measurement of microscopic properties with an integral probe 87
7.1 Interentity magnetic exchange coupling 87
7.2 Ensemble formalism for the entity size determination 90
7.3 Estimation of the entity sizes 94
7.4 Microscopic confirmation of the ensemble model 97
8 Summary and Outlook 101
8.1 Goal-related achievements 101
8.1.1 All-electric read-out of the AF order parameter 101
8.1.2 Electric field induced writing of the AF order parameter 102
8.2 Further achievements 103
8.2.1 Foreseen impact of SCAHM on thin film magnetism 103
8.2.2 Practical optimization routes of magnetoelectric Cr2O3 systems 104
8.2.3 Theoretical work 105
8.3 Future directions 105
8.3.1 Development of Cr2O3-based magnetoelectric systems 105
8.3.2 Applications of SCAHM 106
References 107
Erklärung 113
Acknowledgements 115
Curriculum Vitae 117
Scientific publications, contributions, patents 11