First Successful Attempt in 55 years: Physicists in Russia and Germany Confirm 1969 Experiment Results
A team of researchers, with the participation of physicists from HSE University, replicated the 1969 experiment on superconductivity and its properties. The scientists induced superconductivity by deliberately deteriorating the interfaces between the layers of superconductors and ferromagnets in the system, resulting in better performance of spin valves compared to the classical version, where the interfaces between the layers are ideal. This approach could lead to the development of more efficient devices for data storage and computing. The study findings have been published in the Beilstein Journal of Nanotechnology.
When an electric current passes through a metal wire, it encounters resistance. However, when certain materials are cooled to extremely low temperatures, their resistance vanishes, allowing electricity to flow without any loss. This property is known as superconductivity.
Since the 20th century, scientists have been working on developing a system in which superconductivity could be switched on and off at will. Eventually, a structure was selected in which a superconducting metal interfaced with two ferromagnets influencing its superconducting properties. The arrangement consists of one superconducting layer (S) and two ferromagnetic layers (F), configured as either F-S-F or F-F-S. The alignment of the magnets relative to each other influences the overall superconductivity of the system; by fixing the direction of one magnet and rotating the other, superconductivity can be switched on and off. This phenomenon is known as the superconducting spin valve effect.
It is believed that the maximum spin valve effect can be achieved when transitions between different layers (magnetic and non-magnetic) occur without barriers, defects, or impurities. However, in a 1969 experiment, scientists Deutscher and Meunier demonstrated that the system could function effectively even when dielectric layers—materials that do not conduct electric current but allow electron passage—were introduced. According to Deutscher and Meunier’s findings, a pronounced spin valve effect can be maintained even in a structure that includes dielectric layers. However, other research teams have been unable to replicate this result.
For the first time, a team from the RAS Kazan E. K. Zavoisky Physical-Technical Institute, the Leibniz Institute for Solid State and Materials Research in Dresden, the RAS L. D. Landau Institute for Theoretical Physics, and HSE University successfully replicated the experiment. They created a layered structure using lead as the superconductor and cobalt as the ferromagnet, and experimentally introduced dielectric layers between them. To achieve this, oxygen was added at one stage of the fabrication process to oxidise the interfaces. The resulting oxides were non-conductive to electric current.
The results revealed a pronounced superconducting spin valve effect in the structures obtained. The scientists attribute the result to the dual role of the oxide insulating layers. These layers both reduce the influence of the metallic ferromagnetic layer on the superconducting layer and preserve a proximity effect that enables switching between normal and superconducting states. However, it remains uncertain whether the insulating layers themselves are magnetic. Further research is needed to answer this question.
'From a naive perspective, introducing elements that do not conduct current seems like it would degrade the system. However, it turns out that this is not always the case. Dielectric layers actually enhance the system, while their absence can, conversely, undermine superconductivity,’ explains Yakov Fominov, Professor at the Faculty of Physics and Leading Research Fellow at the International Laboratory for Condensed Matter Physics of HSE University. 'Apparently, we are dealing with a type of superconductivity that is conditionally fragile and sensitive to external influences. When ferromagnets in the system attempt to completely suppress superconductivity, introducing insulating interface layers can restore it.'
The spin valve effect is used in reading information from hard drives, in sensors for measuring magnetic fields in compasses, and in various other devices. The scientists believe that further research on this approach can enhance the performance of superconducting spin valves.
The study was supported by the Russian Science Foundation (project 21-72-20153) and the HSE Basic Research Programme.
See also:
Men Behind the Wheel: Three Times More Violations and Accidents than Women
Men are three times more likely than women to commit traffic violations while driving and to be involved in accidents. Moreover, they are more likely to create situations on the road that are highly dangerous to others. Men are also twice as likely to drive under the influence and nearly one-third more likely to receive a prison sentence for reckless driving. Perhaps it comes down to cultural norms and the different attitudes men and women have toward driving. These are the conclusions reached by Anton Kazun, Assistant Professor at the HSE Faculty of Economic Sciences, and Research Assistant Mikhail Belov.
HSE Scientists Discover How to Predict Charitable Behaviour Through Physiological Reactions
Researchers at the HSE Institute for Cognitive Neuroscience have investigated how the emotional impact of advertising affects the amount people willing to donate to support animal welfare. To accomplish this, the researchers measured physiological responses such as heart rate, electrodermal activity, and facial expressions in individuals viewing various photos of dogs. The findings indicate that willingness to donate is most accurately predicted by heart rate and facial muscle activation. The study has been published in Social Psychology.
'We Are Creating the Medicine of the Future'
Dr Gerwin Schalk is a professor at Fudan University in Shanghai and a partner of the HSE Centre for Language and Brain within the framework of the strategic project 'Human Brain Resilience.' Dr Schalk is known as the creator of BCI2000, a non-commercial general-purpose brain-computer interface system. In this interview, he discusses modern neural interfaces, methods for post-stroke rehabilitation, a novel approach to neurosurgery, and shares his vision for the future of neurotechnology.
Healthy Nutrition Saves Public Funds: Strategies to Reduce Healthcare Costs in Russia
In Russia, the annual cost of treating type 2 diabetes alone exceeds 500 billion roubles. Promoting healthy nutrition programmes can ease the burden on the healthcare system and increase life expectancy. This was the conclusion reached by economists at HSE University after analysing global experiences with government involvement in promoting a healthy lifestyle.
Conscientious Individuals Live Longer
Personality traits such as conscientiousness, emotional stability, and an internal locus of control significantly influence one's lifestyle and longevity. Not only can personality traits influence health through beneficial and harmful habits but can also have a direct effect on mortality. Higher conscientiousness reduces the risk of premature death by 20 percentage points, while higher neuroticism increases it by 12 percentage points. These are the findings from a new study by Ksenia Rozhkova, Junior Research Fellow at the Laboratory for Labour Market Studies of the HSE Faculty of Economic Sciences.
Esports Players Play Better Online
In competitions, esports players, like other athletes, face stress and show worse results due to pressure. A substantial decrease takes place in the performance of esports players during overtime. This effect, however, is significantly mitigated in online competitions compared to live events—the difference can reach 30%. A study by a team of authors from HSE University’s Moscow and Perm campuses and European University Viadrina (Germany) explores the phenomenon of choking under pressure within the context of esports. The study was published in the Journal of Economic Behavior & Organization.
Analysing Genetic Information Can Help Prevent Complications after Myocardial Infarction
Researchers at HSE University have developed a machine learning (ML) model capable of predicting the risk of complications—major adverse cardiac events—in patients following a myocardial infarction. For the first time, the model incorporates genetic data, enabling a more accurate assessment of the risk of long-term complications. The study has been published in Frontiers in Medicine.
A New Tool Designed to Assess AI Ethics in Medicine Developed at HSE University
A team of researchers at the HSE AI Research Centre has created an index to evaluate the ethical standards of artificial intelligence (AI) systems used in medicine. This tool is designed to minimise potential risks and promote safer development and implementation of AI technologies in medical practice.
Russian Scientists Have Studied Marine Worm with Unique Spermatozoa
Russian scientists at Zhirmunsky National Scientific Centre of Marine Biology, HSE University, and Moscow State University have studied Phoronis embryolabi, a rare species of marine invertebrate found in the waters of the Sea of Japan. This species is notable for its unique reproductive system, which includes the development of larvae within the parent’s body and an unusual sperm structure. The study's findings contribute to our understanding of the evolutionary adaptations of marine organisms to extreme conditions. The study has been published in Zoologischer Anzeiger.
Smoking Habit Affects Response to False Feedback
A team of scientists at HSE University, in collaboration with the Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences, studied how people respond to deception when under stress and cognitive load. The study revealed that smoking habits interfere with performance on cognitive tasks involving memory and attention and impairs a person’s ability to detect deception. The study findings have been published in Frontiers in Neuroscience.