scholarly journals Superconductivity-driven ferromagnetism and spin manipulation using vortices in the magnetic superconductor EuRbFe4As4

2021 ◽  
Vol 118 (37) ◽  
pp. e2101101118
Author(s):  
Shigeyuki Ishida ◽  
Daniel Kagerbauer ◽  
Sigrid Holleis ◽  
Kazuki Iida ◽  
Koji Munakata ◽  
...  

Magnetic superconductors are specific materials exhibiting two antagonistic phenomena, superconductivity and magnetism, whose mutual interaction induces various emergent phenomena, such as the reentrant superconducting transition associated with the suppression of superconductivity around the magnetic transition temperature (Tm), highlighting the impact of magnetism on superconductivity. In this study, we report the experimental observation of the ferromagnetic order induced by superconducting vortices in the high-critical-temperature (high-Tc) magnetic superconductor EuRbFe4As4. Although the ground state of the Eu2+ moments in EuRbFe4As4 is helimagnetism below Tm, neutron diffraction and magnetization experiments show a ferromagnetic hysteresis of the Eu2+ spin alignment. We demonstrate that the direction of the Eu2+ moments is dominated by the distribution of pinned vortices based on the critical state model. Moreover, we demonstrate the manipulation of spin texture by controlling the direction of superconducting vortices, which can help realize spin manipulation devices using magnetic superconductors.

2006 ◽  
Vol 20 (29) ◽  
pp. 1901-1908 ◽  
Author(s):  
V. P. S. AWANA ◽  
H. KISHAN ◽  
E. TAKAYAMA-MUROMACHI ◽  
A. V. NARLIKAR

Substitution of both Co and Mo at Ru -site in RuSr 2 Eu 1.5 Ce 0.5 Cu 2 O 10-δ system takes place iso-structurally in tetragonal structure (space group I4/mmm) with full solubility. The resistance versus temperature (R versus T) behavior of the pristine sample confirmed superconductivity [Formula: see text] around 25 K. The DC magnetization data (M versus T) for the same sample revealed magnetic transition (T mag ) at 140 K followed by superconducting transition [Formula: see text] at 32 K. With progressive Co substitution at Ru -site both [Formula: see text] and [Formula: see text] decrease monotonically and superconductivity is not observed for x ≥ 0.10 (10 at%). The magnetic behavior of materials with Co up to x = 0.2 preserves the magnetic structure of the parent RuSr 2 Eu 1.5 Ce 0.5 Cu 2 O 10-δ compound. For 0.8 ≥ x ≥ 0.2 a clear antiferromagnetic transition at TN=31 K is observed regardless of Co content. In the case of Mo -doped ruthenocuprates Ru 1-x Mo x Sr 2 Eu 1.5 Ce 0.5 Cu 2 O 10-δ, it has been found that the magnetic transition temperature decreases with x. The samples of x = 0.8 and 1.0 are found to have no magnetic or superconducting effects. The values of the superconducting transition temperature obtained from the resistivity versus temperature data increase by 4.5 and 7.0 K for x = 0.2 and 0.4 respectively, and then decrease by 17 K for x = 0.6. The observed variation of Tc with x in case of Mo has been explained in terms of a theory which combines the effects of weakening magnetic behavior and reducing carrier concentration in a phenomenological manner.


2017 ◽  
pp. 114-127
Author(s):  
M. Klinova ◽  
E. Sidorova

The article deals with economic sanctions and their impact on the state and prospects of the neighboring partner economies - the European Union (EU) and Russia. It provides comparisons of current data with that of the year 2013 (before sanctions) to demonstrate the impact of sanctions on both sides. Despite the fact that Russia remains the EU’s key partner, it came out of the first three partners of the EU. The current economic recession is caused by different reasons, not only by sanctions. Both the EU and Russia have internal problems, which the sanctions confrontation only exacerbates. The article emphasizes the need for a speedy restoration of cooperation.


2020 ◽  
Vol 8 (3) ◽  
pp. 3-17
Author(s):  
Elena Blagoeva

The impact of the last global economic crisis (2008) on the European economy put a strain on higher education (HE), yet it also pushed the sector towards intensive reforms and improvements. This paper focuses on the “Strategy for the Development of Higher Education in the Republic of Bulgaria 2014-2020”. With a case study methodology, we explore the strategic endeavours of the Bulgarian government to comply with the European directions and to secure sustainable growth for the HE sector. Our research question is ‘How capable is the Bulgarian HE Strategy to overcome the economic and systemic restraints of Bulgarian higher education?’. Because the development of strategies for HE within the EU is highly contextual, a single qualitative case study was chosen as the research approach. HE institutions are not ivory towers, but subjects to a variety of external and internal forces. Within the EU, this is obviated by the fact that Universities obtain their funds from institutions such as governments, students and their families, donors, as well as EU-level programmes. Therefore, to explore how these pressures interact to affect strategic action on national level, the case method is well suited as it enabled us to study the phenomena thoroughly and deeply. The paper suggests the actions proposed within the Strategy have the potential to overcome the delay, the regional isolation and the negative impact of the economic crisis on the country. Nevertheless, the key elements on which the success or failure of this Strategy hinges are the control mechanisms and the approach to implementation. Shortcomings in these two aspects of strategic actions in HE seem to mark the difference between gaining long-term benefits and merely saving face in front of international institutions.


Author(s):  
Valentyna Bohatyrets ◽  
Liubov Melnychuk ◽  
Yaroslav Zoriy

This paper seeks to investigate sustainable cross-border cooperation (CBC) as a distinctive model of interstate collaboration, embedded in the neighboring borderland regions of two or more countries. The focus of the research revolves around the establishment and further development of geostrategic, economic, cultural and scientific capacity of the Ukrainian-Romanian partnership as a fundamental construct in ensuring and strengthening the stability, security and cooperation in Europe. This research highlights Ukraine’s aspirations to establish, develop and diversify bilateral good-neighborly relations with Romania both regionally and internationally. The main objective is to elucidate Ukraine-Romania cross-border cooperation initiatives, inasmuch Ukraine-Romania CBC has been stirring up considerable interest in terms of its inexhaustible historical, cultural and spiritual ties. Furthermore, the similarity of the neighboring states’ strategic orientations grounds the basis for development and enhancement of Ukraine-Romania cooperation. The authors used desk research and quantitative research to conclude that Ukraine-Romania CBC has the impact not only on the EU and on Ukraine multi-vector foreign policy, but it also has the longer-term global consequences. In the light of the current reality, the idea of introducing and reinforcing the importance of Cross-Border Cooperation (CBC) sounds quite topical and relevant. This research considers a number of explanations for Ukraine-Romania Cross-Border Cooperation as a key element of the EU policy towards its neighbors. Besides, the subject of the research is considered from different perspectives in order to show the diversity and complexity of the Ukraine-Romania relations in view of the fact that sharing common borders we are presumed to find common solutions. As the research has demonstrated, the Ukraine-Romania cross border cooperation is a pivotal factor of boosting geostrategic, economic, political and cultural development for each participant country, largely depending on the neighboring countries’ cohesion and convergence. Significantly, there is an even stronger emphasis on the fact that while sharing the same borders, the countries share common interests and aspirations for economic thriving, cultural exchange, diplomatic ties and security, guaranteed by a legal framework. The findings of this study have a number of important implications for further development and enhancement of Ukraine-Romania cooperation. Accordingly, the research shows how imperative are the benefits of Romania as a strategic partner for outlining top priorities of Ukraine’s foreign policy.


2008 ◽  
Author(s):  
Giuseppe Carone ◽  
Declan Costello ◽  
Nuria Diez Guardia ◽  
Per Eckefeldt ◽  
Gilles Mourre

2012 ◽  
Author(s):  
Jonatan Groba ◽  
Juan Angel Lafuente ◽  
Pedro Serrano
Keyword(s):  

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