1. Joined
    06 Mar '12
    Moves
    625
    19 Aug '12 20:082 edits
    Apparently there has been a significant advance in the field of spintronics just a few days ago with the “first ever direct mapping of the formation of a persistent spin helix in a semiconductor” ( see link below ) .
    But what the hell IS a “spin helix”? I have never heard of this term before and I tried googling it but got nowhere. The link I have about the breakthough doesn't say much about what a "spin helix" is other than it is " a stripe-like pattern key to the success of spintronics and originally theoretically proposed back in 2003".

    Anyone?

    Here is the link about this breakthrough:

    http://www.bit-tech.net/news/hardware/2012/08/14/ibm-spintronics/1
    “....

    IBM researchers boast of spintronics breakthrough
    Published on 14th August 2012 by Gareth Halfacree


    IBM has released details of a successful experiment resulting in the first ever direct mapping of the formation of a persistent spin helix in a semiconductor - a major step on the path to commercialising spintronic technology.

    Spintronics, a portmanteau of 'spin,' 'transport' and 'electronics,' promises to revolutionise the semiconductor market. Spintronic components use the spin of the electron to store a zero or a one, rather than the charge of the electron. The result is the storage and transmission of data - and even calculations - with no energy dissipation, and a resulting reduction in the power required. Spintronic components would also blur the barrier between memory and storage, producing high-speed non-volatile storage which could easily be used as either memory or mass storage.

    Sadly, spintronics is a technology which remains tantalisingly out of grasp, requiring several major breakthroughs before it can be commercially implemented. Chief among these was the problem of whether electron spins possessed the capability to preserve the encoded information long enough before rotating - a theoretical possibility, but one unproven.

    Researches from IBM Research and the Solid State Physics Lab at ETH Zurich have now answered that question with a resounding 'yes,' in an experiment which lengthened the spin lifetime of electronics thirty-fold to 1.1 nanoseconds - a timescale handily compatible with the cycle of a 1GHz processor.

    The breakthrough, IBM's Gian Salis explains, came from an observation that electron spins move in a manner similar to dancers in the Viennese waltz - shifting tens of micrometres in a semiconductor with their orientation rotating along the path in perfect synchronisation.

    'If all couples start with the women facing north, after a while the rotating pairs are oriented in different directions,' Salis explains of his group's discovery. 'We can now lock the rotation speed of the dancers to the direction they move. This results in a perfect choreography where all the women in a certain area face the same direction. This control and ability to manipulate and observe the spin is an important step in the development of spin-based transistors that are electrically programmable.'

    Using short laser pulses to monitor the evolution of thousands of electron spins created simultaneously in a very small spot on a gallium arsenide semiconductor, IBM researchers were able to observe a persistent spin helix - a stripe-like pattern key to the success of spintronics and originally theoretically proposed back in 2003 but never before directly observed.

    Sadly, despite representing a major breakthrough in the field, spintronics remains a lab-based pursuit: IBM warns that its experiments took place at a temperature of 40 Kelvin, or -233 degrees Celsius - something even the most impressive off-the-shelf liquid cooling system is unlikely to achieve in commercial devices.
    ...”
  2. Subscribersonhouse
    Fast and Curious
    slatington, pa, usa
    Joined
    28 Dec '04
    Moves
    52619
    20 Aug '12 10:462 edits
    Originally posted by humy
    Apparently there has been a significant advance in the field of spintronics just a few days ago with the “first ever direct mapping of the formation of a persistent spin helix in a semiconductor” ( see link below ) .
    But what the hell IS a “spin helix”? I have never heard of this term before and I tried googling it but got nowhere. The link I have about the b lf liquid cooling system is unlikely to achieve in commercial devices.
    ...”
    I am surprised it works even at 40 K. I work with cryogenics all the time, my cryo pumps internally get down to 10-13 degrees Kelvin all the time, they have to to trap gasses on an activated carbon christmas tree like structure, where gasses check in but they don't check out so there is a constant flow of gas in a vacuum system hitting the cold head which means the vacuum gets better and better all the time till there is equilibrium between either physical leaks or virtual leaks, the latter being places say, inside surface roughness of metals, atmospheric gasses or humidity hides out and slowly escapes. That latter can be dealt with by zapping the inside surfaces with UV but we don't go to that extant, just happy getting a pressure close to 1E-8 torr range.

    So there are ways of getting down to that temperature but it takes a cryo-compressor and the mechanism of the cold head which includes a piston moving up and down slowly, compared to a motor, one cycle roughly every second.

    The cryo compressor itself consumes a couple thousand watts so the resulting system had better be extremely powerful as a computer to justify that much power expenditure at least at this stage of development of such systems.

    The actual cooling power of the cold head is only about 1 percent efficient, I don't know why, well it has to due with the amount of energy it takes to pump helium into the cold head, the flow it takes, but the actual wattage rating of the cold head is only a few watts, maybe ten watts max but the equipment to cool it down to low kelvin numbers consumes thousands of watts, not a great percentage. If they can get that down to the level of efficiency of a modern household refrigerator they might have something commercial but till then, they better have an extremely powerful computer as the result of spintronics before it comes out of the labs.

    The cooling gas, btw, for such cyro pumps is helium. We have to go to great engineering lengths just to keep the stuff from leaking away and we do a great job of that in the cryo pump compressor.