- Email: [email protected]
Magnets rival power-hungry transistors
For daily news stories, visit newscientist.com/news
STACKS of nanomagnets could make future supercomputers run leaner. Microchips made from tiny magnets rather than conventional powerhungry transistors may enable intensive number-crunching tasks like codebreaking or image-processing using a fraction of the power. In traditional computer chips, the bits of information, 0s and 1s, are represented by voltages across a transistor, each of which needs its own wire. But magnets can do the same job by switching their pole orientation: pointing north-south represents 1, say, and south-north is 0. Flipping poles takes less energy than running current through a wire, so they need less power to run. Nanomagnets have already been placed on microchip surfaces in a single layer, but they need extra space to work properly. Building them in 3D is critical if they are to rival the density of transistor-based designs. Now, a team led by Irina Eichwald at the Technical University of Munich in Germany has worked out how to grow a chip with number-crunching layers 100 nanomagnets deep. The team made a logic gate, one of the essential building blocks of a computer, from stacked arrays of nanomagnets. Instead of wires, a handful of magnets above the chip induced magnetic fields. The magnets then flip their orientation one after the other, like dominoes, to the magnet performing the actual operation. In a test, the magnetic chip used 1/35th of the power a transistor used (Nanotechnology, doi.org/tz3). “A huge number of computing processes can now be done simultaneously with very low power consumption as you don’t need the connecting wires transistors need. You only need to generate a magnetic field across the chip,” says Eichwald. It has potential, says Peter Bentley at University College London. “It’s yet another technology joining the race to replace silicon.” Paul Marks n
Mark Tomalty/Aurora Photos
Magnets rival power-hungry transistors
–I fancy Barbados, how about you?–
Songbirds really do fly south for the winter EVERY year many birds fly away to University of Chicago and his distant lands. But even though colleagues have strong evidence their extraordinary journeys are that most migrants hail from the familiar to us all, it turns out our north, not the south. understanding of them was, quite Winger’s team studied the literally, backwards. largest group of American Most of the songbirds that songbirds, including over migrate between North America 800 species of sparrows, warblers and the tropics do it to escape and blackbirds. Other researchers harsh northern winters. That had already developed a good squares with the folk belief that “If migration is driven by “birds fly south for the winter”, frigid winters, might birds but is the exact opposite of what migrate less as the world biologists thought – that tropical gets warmer?” birds venture north to escape overcrowding. For years, the received wisdom family tree of these birds. was that most intercontinental The team began with the songbird migrations arose when distribution of each species tropical birds flew north during today, then worked their way back the summer breeding season, to along the family tree, inferring escape the intense competition where earlier species had lived. for space and food in the crowded Whenever intercontinental tropics. This explanation seemed migration arose, they noted simplest: most songbirds in the whether the bird lived in the Americas, including those that do tropics or the temperate zone. not migrate, live in the South They found that long-distance American tropics, and almost migration was twice as likely to every migratory bird species has arise in temperate ancestors as close relatives in the tropics. tropical ones (PNAS, doi.org/t2k). Now Ben Winger of the “We’re not saying it only
happens one way,” says Winger. “But it happens more often by moving winter ranges toward the south.” It does look like the songbirds Winger studied began in the north, says Rauri Bowie of the University of California, Berkeley. However, these birds’ common ancestor came to the Americas from northern Asia, so that could be a historical accident. The question is, did migration arise in the same way in groups that originated in the tropics? Winger’s findings suggest that birds choose to migrate or stay at home based on the severity of the threat of winter, not the benefits of northern summers. If migration really is driven by frigid winters, might birds then migrate less as the world gets warmer? Winger found many cases of migratory birds shifting to a settled existence. That adaptability may prove useful as the climate changes. “Migration is a fairly flexible trait that can change rapidly,” says Irby Lovette of Cornell University in Ithaca, New York. “We should certainly expect... changes in the migratory strategies of birds as the world changes around them.” Bob Holmes n 9 August 2014 | NewScientist | 9
STACKS of nanomagnets could make future supercomputers run leaner. Microchips made from tiny magnets rather than conventional powerhungry transistors may enable intensive number-crunching tasks like codebreaking or image-processing using a fraction of the power. In traditional computer chips, the bits of information, 0s and 1s, are represented by voltages across a transistor, each of which needs its own wire. But magnets can do the same job by switching their pole orientation: pointing north-south represents 1, say, and south-north is 0. Flipping poles takes less energy than running current through a wire, so they need less power to run. Nanomagnets have already been placed on microchip surfaces in a single layer, but they need extra space to work properly. Building them in 3D is critical if they are to rival the density of transistor-based designs. Now, a team led by Irina Eichwald at the Technical University of Munich in Germany has worked out how to grow a chip with number-crunching layers 100 nanomagnets deep. The team made a logic gate, one of the essential building blocks of a computer, from stacked arrays of nanomagnets. Instead of wires, a handful of magnets above the chip induced magnetic fields. The magnets then flip their orientation one after the other, like dominoes, to the magnet performing the actual operation. In a test, the magnetic chip used 1/35th of the power a transistor used (Nanotechnology, doi.org/tz3). “A huge number of computing processes can now be done simultaneously with very low power consumption as you don’t need the connecting wires transistors need. You only need to generate a magnetic field across the chip,” says Eichwald. It has potential, says Peter Bentley at University College London. “It’s yet another technology joining the race to replace silicon.” Paul Marks n
Mark Tomalty/Aurora Photos
Magnets rival power-hungry transistors
–I fancy Barbados, how about you?–
Songbirds really do fly south for the winter EVERY year many birds fly away to University of Chicago and his distant lands. But even though colleagues have strong evidence their extraordinary journeys are that most migrants hail from the familiar to us all, it turns out our north, not the south. understanding of them was, quite Winger’s team studied the literally, backwards. largest group of American Most of the songbirds that songbirds, including over migrate between North America 800 species of sparrows, warblers and the tropics do it to escape and blackbirds. Other researchers harsh northern winters. That had already developed a good squares with the folk belief that “If migration is driven by “birds fly south for the winter”, frigid winters, might birds but is the exact opposite of what migrate less as the world biologists thought – that tropical gets warmer?” birds venture north to escape overcrowding. For years, the received wisdom family tree of these birds. was that most intercontinental The team began with the songbird migrations arose when distribution of each species tropical birds flew north during today, then worked their way back the summer breeding season, to along the family tree, inferring escape the intense competition where earlier species had lived. for space and food in the crowded Whenever intercontinental tropics. This explanation seemed migration arose, they noted simplest: most songbirds in the whether the bird lived in the Americas, including those that do tropics or the temperate zone. not migrate, live in the South They found that long-distance American tropics, and almost migration was twice as likely to every migratory bird species has arise in temperate ancestors as close relatives in the tropics. tropical ones (PNAS, doi.org/t2k). Now Ben Winger of the “We’re not saying it only
happens one way,” says Winger. “But it happens more often by moving winter ranges toward the south.” It does look like the songbirds Winger studied began in the north, says Rauri Bowie of the University of California, Berkeley. However, these birds’ common ancestor came to the Americas from northern Asia, so that could be a historical accident. The question is, did migration arise in the same way in groups that originated in the tropics? Winger’s findings suggest that birds choose to migrate or stay at home based on the severity of the threat of winter, not the benefits of northern summers. If migration really is driven by frigid winters, might birds then migrate less as the world gets warmer? Winger found many cases of migratory birds shifting to a settled existence. That adaptability may prove useful as the climate changes. “Migration is a fairly flexible trait that can change rapidly,” says Irby Lovette of Cornell University in Ithaca, New York. “We should certainly expect... changes in the migratory strategies of birds as the world changes around them.” Bob Holmes n 9 August 2014 | NewScientist | 9