Physicists create anti ferromagnet that may help develop, monitor key materials.
From the moment when physicists discovered superconductors — materials that conduct electricity without resistance at extremely low temperatures — they wondered whether they might be able to develop materials that exhibit the same properties at warmer temperatures.
The key to doing so, a group of Harvard scientists say, may lie in another exotic material known as an antiferromagnet.
Led by physics professor Markus Greiner, a team of physicists has taken a crucial step toward understanding those materials by creating a quantum antiferromagnet from an ultracold gas of hundreds of lithium atoms. The work is described in a May 25 paper published in the journal Nature.
“We have created a model system for real materials … and now, for the first time, we can study this model system in a regime where classical computers get to their limit,” Greiner said. “Now, we can poke and prod our antiferromagnet. It’s a beautifully tunable system, and we can even freeze time to take a snapshot of where the atoms are. That’s something you won’t be able to do with an actual solid.”
But what, exactly, is an antiferromagnet?
Traditional magnets, the kind that you can stick to your refrigerator, work because the electron spins in the material are aligned, allowing them to work in unison. In an antiferromagnet, however, those spins are arranged in a checkerboard pattern. One spin may be pointed north, while the next is pointing south, and so on.
Understanding antiferromagnets is important, Greiner and physics professor Eugene Demler said, because experimental work has suggested that, in the most promising high-temperature superconductors — a class of copper-containing compounds known as cuprates — the unusual state may be a precursor to high-temperature superconductivity.
Currently, Demler said, the best cuprates display superconductivity at about minus 160 degrees Fahrenheit, which is cold by everyday standards, but far higher than for any other type of superconductor. That temperature is also warm enough to allow practical applications of cuprate superconductors in telecommunications, transportation, and in the generation and transmission of electric power.
“This antiferromagnet stage is a crucial stepping-stone for understanding superconductors,” said Demler, who led the team providing theoretical support for the experiments. “Understanding the physics of these doped antiferromagnets may be the key to high-temperature superconductivity.”
To build one, Greiner and his team trapped a cloud of lithium atoms in a vacuum and then used a technique they dubbed “entropy redistribution” to cool them to just 10 billionths of a degree above absolute zero, which allowed them to observe the unusual physics of antiferromagnets.
“We have full control over every atom in our experiment,” said Daniel Greif, the postdoctoral fellow working in Greiner’s lab. “We use this control to implement a new cooling scheme, which allows us to reach the lowest temperatures so far in such systems.”
View at the original source
The key to doing so, a group of Harvard scientists say, may lie in another exotic material known as an antiferromagnet.
Led by physics professor Markus Greiner, a team of physicists has taken a crucial step toward understanding those materials by creating a quantum antiferromagnet from an ultracold gas of hundreds of lithium atoms. The work is described in a May 25 paper published in the journal Nature.
“We have created a model system for real materials … and now, for the first time, we can study this model system in a regime where classical computers get to their limit,” Greiner said. “Now, we can poke and prod our antiferromagnet. It’s a beautifully tunable system, and we can even freeze time to take a snapshot of where the atoms are. That’s something you won’t be able to do with an actual solid.”
But what, exactly, is an antiferromagnet?
Traditional magnets, the kind that you can stick to your refrigerator, work because the electron spins in the material are aligned, allowing them to work in unison. In an antiferromagnet, however, those spins are arranged in a checkerboard pattern. One spin may be pointed north, while the next is pointing south, and so on.
Understanding antiferromagnets is important, Greiner and physics professor Eugene Demler said, because experimental work has suggested that, in the most promising high-temperature superconductors — a class of copper-containing compounds known as cuprates — the unusual state may be a precursor to high-temperature superconductivity.
Currently, Demler said, the best cuprates display superconductivity at about minus 160 degrees Fahrenheit, which is cold by everyday standards, but far higher than for any other type of superconductor. That temperature is also warm enough to allow practical applications of cuprate superconductors in telecommunications, transportation, and in the generation and transmission of electric power.
“This antiferromagnet stage is a crucial stepping-stone for understanding superconductors,” said Demler, who led the team providing theoretical support for the experiments. “Understanding the physics of these doped antiferromagnets may be the key to high-temperature superconductivity.”
To build one, Greiner and his team trapped a cloud of lithium atoms in a vacuum and then used a technique they dubbed “entropy redistribution” to cool them to just 10 billionths of a degree above absolute zero, which allowed them to observe the unusual physics of antiferromagnets.
“We have full control over every atom in our experiment,” said Daniel Greif, the postdoctoral fellow working in Greiner’s lab. “We use this control to implement a new cooling scheme, which allows us to reach the lowest temperatures so far in such systems.”
View at the original source
No comments:
Post a Comment