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Category: particle physics – Page 6

Interface-controlled antiferromagnetic tunnel junctions offer new path for next-gen spintronics

A research team led by Prof. Shao Dingfu at the Institute of Solid State Physics, the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, has unveiled a new mechanism for achieving strong spin polarization using antiferromagnetic metal interfaces.

Their findings, published in Newton recently, propose a third prototype of antiferromagnetic tunnel junction (AFMTJ), paving the way for faster and denser spintronic devices.

As electronics demand smaller size, higher speed, and lower energy use, spintronics—using both electron charge and spin—offers a strong alternative to traditional devices. Magnetic tunnel junctions (MTJs), a key spintronics technology, are already used in but face limits due to slow response speeds and unwanted magnetic fields from their ferromagnetic parts.

Toward new physics: First-ever double crystal channeling observed

Might two bent crystals pave the way to finding new physics? The Standard Model of particle physics describes our world at its smallest scales exceptionally well. However, it leaves some important questions unanswered, such as the imbalance between matter and antimatter, the existence of dark matter and other mysteries.

One method to find “new physics” beyond the Standard Model is to measure the properties of different particles as precisely as possible and then compare measurement with theory. If the two don’t agree, it might hint at new physics and let us slowly piece together a fuller picture of our universe—like pieces of a jigsaw puzzle.

An example of particles that physicists wish to study more closely are “charm baryons” such as the “Lambda-c-plus” (Λc+) which is a heavier “cousin” of the proton, consisting of three quarks: one up, one down and one charm. These particles decay after less than a trillionth of a second (10-13 s), which makes any measurement of their properties a race against time. Some of their properties have not yet been measured to high precision, leaving room for new physics to hide.

Antiferromagnets outperform ferromagnets in ultrafast, energy-efficient memory operations

Advances in spintronics have led to the practical use of magnetoresistive random-access memory (MRAM), a non-volatile memory technology that supports energy-efficient semiconductor integrated circuits.

Recently, antiferromagnets— with no net magnetization—have attracted growing attention as promising complements to conventional ferromagnets. While their properties have been extensively studied, clear demonstrations of their technological advantages have remained elusive.

Now, researchers from Tohoku University, the National Institute for Materials Science (NIMS), and the Japan Atomic Energy Agency (JAEA) have provided the first compelling evidence of the unique benefits of antiferromagnets.

“Heavy” Electrons Hold the Key to a New Type of Quantum Computer

Discovery of Planckian time limit offers new opportunities for quantum technologies. A collaborative team of researchers in Japan has identified “heavy fermions”—electrons with greatly increased effective mass—that display quantum entanglement controlled by Planckian time, the fundamental unit of

X-ray and Radio go ‘Hand in Hand’ in New Image

In 2009, NASA’s Chandra X-ray Observatory released a captivating image: a pulsar and its surrounding nebula that is shaped like a hand. Since then, astronomers have used Chandra and other telescopes to continue to observe this object. Now, new radio data from the Australia Telescope Compact Array (ATCA) has been combined with Chandra’s X-ray data to provide a fresh view of this exploded star and its environment, to help understand its peculiar properties and shape.

At the center of this new image lies the pulsar B1509-58, a rapidly spinning neutron star that is only about 12 miles in diameter. This tiny object is responsible for producing an intricate nebula (called MSH 15–52) that spans over 150 light-years, or about 900 trillion miles. The nebula, which is produced by energetic particles, resembles a human hand with a palm and extended fingers pointing to the upper right in X-rays.

The collapse of a massive star created the pulsar when much of the star crashed inward once it burned through its sustainable nuclear fuel. An ensuing explosion sent the star’s outer layers outward into space as a supernova.

A blueprint for error-corrected fermionic quantum processors

An international research team led by Robert Ott and Hannes Pichler has developed a novel architecture for quantum processors that is specifically designed for simulating fermions—particles such as electrons. The method can be implemented using technologies already available today.

Growth strategy enhances efficiency and stability of perovskite solar cells

Photovoltaics (PVs), technological systems that can convert sunlight into electricity are among the most promising and widely adopted clean energy solutions worldwide. While existing silicon-based solar cells have already achieved remarkable performances, energy engineers have been working to develop other photovoltaic technologies that could be even more durable, efficient and affordable.

An emerging type of solar cells that could be manufactured at a lower cost, while still retaining good efficiencies, are those based on a class of materials with a characteristic arrangement of atoms, known as perovskites. These cells, known as perovskite solar cells (PSCs), have been found to attain high power conversion efficiencies and are based on materials that could be easier to synthesize when compared to silicon wafers.

Despite their potential, PSCs still face considerable limitations that have so far prevented their widespread deployment and commercialization. Most notably, improving the efficiency of these cells has been found to adversely impact their stability over time, and vice versa.

Two new methods push graphene’s electronic quality beyond traditional semiconductors

Graphene, a single sheet of carbon atoms arranged in a honeycomb lattice, is known for its exceptional strength, flexibility and conductivity. However, despite holding the world record for room-temperature electron mobility, graphene’s performance at cryogenic temperatures has remained below that of the best gallium arsenide (GaAs)-based semiconductor systems, which have benefited from many decades of refinement.

One key obstacle is electronic disorder. In practical devices, is highly sensitive to stray electric fields from charged defects in surrounding materials. These imperfections create spatial fluctuations in , known as electron-hole puddles, that scatter electrons and limit mobility. This disorder has prevented graphene from realizing its full potential as an ultra-clean electronic system.

Now, in two parallel studies, researchers from the National University of Singapore (NUS) and The University of Manchester (UK) report distinct strategies that finally push graphene past this long-standing benchmark. The results set new records for electron mobility, matching and in some cases surpassing GaAs in both transport and quantum mobility, and enabling the observation of quantum effects in unprecedented conditions.

How a superfluid simultaneously becomes a solid

In everyday life, all matter exists as either a gas, liquid, or solid. In quantum mechanics, however, it is possible for two distinct states to exist simultaneously. An ultracold quantum system, for instance, can exhibit the properties of both a fluid and a solid at the same time.

The Synthetic Quantum Systems research group at Heidelberg University has now demonstrated this phenomenon using a new experimental approach, by feeding a small amount of energy into a superfluid. They showed that, in a driven quantum system of this kind, propagate at two different speeds, which points toward coexisting liquid and solid states, a hallmark of supersolidity. The work is published in the journal Nature Physics.

This surprising and seemingly contradictory behavior of two states of matter existing at the same time does not occur at room temperature. But at ultralow temperatures, takes over, and matter can exhibit fundamentally different properties. When atoms are cooled to such low temperatures, their wave-like nature is dominant. If brought close enough together, many particles merge into one large wave, known as a Bose-Einstein condensate. This state is a superfluid, a fluid that flows without friction.

A New Understanding of Einstein-Rosen Bridges

The formulation of quantum field theory in Minkowski spacetime, which emerges from the unification of special relativity and quantum mechanics, is based on treating time as a parameter, assuming a fixed arrow of time, and requiring that field operators commute for spacelike separations. This procedure is questioned in the context of quantum field theory in curved spacetime (QFTCS). In 1935, Einstein and Rosen (ER), in their seminal paper [1] proposed that “a particle in the physical Universe has to be described by mathematical bridges connecting two sheets of spacetime” which involved two arrows of time. We further establish that the quantum effects at gravitational horizons aesthetically involve the physics of quantum inverted harmonic oscillators that have phase space horizons. Recently proposed direct-sum quantum theory reconciles the ER’s vision by introducing geometric superselection sectors associated with the regions of spacetime related by discrete transformations. This new understanding of the ER bridges promises a unitary description of QFTCS, along with observer complementarity. Furthermore, we present compelling evidence for our new understanding of ER bridges in the form of large-scale parity asymmetric features in the cosmic microwave background, which is statistically 650 times stronger than the standard scale-invariant power spectrum from the typical understanding of inflationary quantum fluctuations when compared with the posterior probabilities associated with the model given the data. We finally discuss the implications of this new understanding in combining gravity and quantum mechanics.

Gravity and quantum mechanics.

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