Nickel 'nanodots' could mean tiny hard drives

[Alistar7]

Nanoscopic dots of nickel that could be used to store terabytes of data in a computer chip just a few centimetres wide have been created by US researchers.



http://www.newscientist.com/news/news.jsp?id=ns99996362

 

[thermalpaste]

very interesting read....thx for the link.

 

[Zero Plasma]

Really neato

 

[BW86]

cool read

five thousand gigabytes - to be packed into computer drive roughly the size of postage stamp.
:roll:

 

[Bassyhead]

wow neat read

 

[RelaxTheMind]

would probably take me about 10 years to fill up that drive. even if i tried.

vicflo

 

[darfur]

Neat and all, but I thought that one problem with increasing the density of modern hard drives is that the magnetic fields created by all the little bits start to interfere with one another.

How is this any different at 10 times the density (well 10 times smaller anway)?

 

[jagec]

Originally posted by: RelaxTheMind
would probably take me about 10 years to fill up that drive. even if i tried.

vicflo

really? I could do it in a couple months

 

[cheesehead]

Heh. I could fit the entire blockbuster into a PDA!
Of course, you would still have problems relating to the fact that it's hard to make a magnetic field that small. However, this could mean 200GB 1.8" hard drives, which, due to small platter size, we could spin at 15K or above.
I wish I was smarter....then I could get a job making these things.

 

[darfur]

Originally posted by: darfur
Neat and all, but I thought that one problem with increasing the density of modern hard drives is that the magnetic fields created by all the little bits start to interfere with one another.

How is this any different at 10 times the density (well 10 times smaller anway)?

Anyone?

 

[klaviernista]

Originally posted by: darfur

Originally posted by: darfur
Neat and all, but I thought that one problem with increasing the density of modern hard drives is that the magnetic fields created by all the little bits start to interfere with one another.

How is this any different at 10 times the density (well 10 times smaller anway)?

Anyone?

I examine patent applications for magentic media at the patent and trademark office. The problem you are describing has been around for a long time, as has so called "nanodot" media. This problem is called "intergranular exchange coupling" and contributes to increased noise in high density magentic media.

This problem arose as a result of the industry striving towards increased recording density. One way to get increased recording density is to reduce the size of the grains in magnetic layer (Basically, 1 grain=1 bit, so more grains =more bits per square inch). The problem with this is that as you reduce grain size, the coercivity (basically the strength by which a magnetic domain is held in a fixed direction) decreases. In other words, the orientation of each domain in each bit becomes more susceptible to being influenced by external magentic fields. Well, as each grain is magnetic and the coercivity of each grain is low at small grain sizes, the magnetic field of each grain impacts the orientation of the domain in each surrounding grain. As a result, the noise of the media is increased.

Industry has come up with a variety of ways to combat this problem. the most common way to prevent or reduce this type of coupling is to introduce Cr into the magnetic layer. Cr only has a certain solubilty in the crystalline lattice of a Co alloy (Co is the most common element used for the magentic layers in magentic media). When the CoCr magnetic layer is formed, it is first deposited (via sputtering or cvd) and then annealed. As a result of the annealing step, excess Cr segregates from within the crystalline grain into the area between adjacent grains (called the grain boundary). By controlling the amount of Cr which segregates, the spacing between grains is controlled. As you probably know, magnetic field intensity decreases as the distance from its origin increases. Thus, the influence of each grains magnetic field on surrounding grains is substantially reduced by the introduction of Cr into the grain boundary. In addition, non-magentic oxides such as SiO2 and TiO2 have also been used to segregate grains.

So, with nanodot media and quantum dot media, it is likely that some form of segregant will be utilized to separate each dot, or the dots themselves will be spaced apart when they are dposited so as to minimize this type of grain coupling. Many quantum dot media are formed by self assembly methods, so control over spacing between each dot can usually be controlled realtively easily.

Hope that helps. Probably more info then you wanted, but if you have more questions about magentic media let me know.

 

[klaviernista]

One other major issue is that while nanodot media might exist which could theoretically contain terabytes of data per square inch, a head or other recording instrument that can read and record at that density does not. Its a resolution problem basically. To read data from a magnetic disc, a magnetic head flys over the surface of the media. The head has a magnetic layer which has a domain that rotates in response to external magenetic fields, thus changing its resistance (in other words, its magnetoresistive). Well, the sensitivity of a head (meaning the ease by whih the domain of that magnetic layer would have to rotate) that would be needed to read data from dots as small as these would have to be tremendous, and it would have to be able to reliably distinguish between the magnetic field of the dot it is reading and the fields of those dots only a few angstroms away. The problem with this is that to read magnetic fields as weak as those generated by these tiny dots, the domain of the magnetic layer in the magnetoresistive head would have to rotate very very easily (it would have to have very low coercivity). When magentic domains have low coercivity it is difficult to keep them oriented in one direction, because heat from the atmosphere starts to become sufficent to rotate these domains on their own. So there is a balancing problem between sensitivity and having oriented domains. Essentially, you need both, but they are in direct competition with one another.

I'm not saying its not possible, I'm just saying that its a long way off.

Oh, and the article states something to the effect of: these researchers have created 5nm nickel dots, which are about 10 times smaller then those previously produced. It shouold read "those previously produced, by them." I personally worked on a project at the Naval Research Laboratory a number of years back where I used a reverse micelle synthesis technique to fabricate spherical 3 nm Iron Oxide (superparamagnetic) and 11nm FePt (ferromagnetic) nanoparticles. Further, the use of the reverse micelle technique to create magnetic nanoparticles on the scale asserted by these researchers has been known since the early 90's, and the potential use of these particles as memory has been around since the mid 90's as well. So to me there is nothing really new about wehat these guys have done.

I'm not trying ot sound arrogant, I'm just letting you know that this isn;t really new is all. Still interesting tech though.

 

[Alistar7]

Originally posted by: klaviernista
One other major issue is that while nanodot media might exist which could theoretically contain terabytes of data per square inch, a head or other recording instrument that can read and record at that density does not. Its a resolution problem basically. To read data from a magnetic disc, a magnetic head flys over the surface of the media. The head has a magnetic layer which has a domain that rotates in response to external magenitc fields, thus changing its reisstance (in other words, its magneoresistive). Well, the sensitivity of a head (meaning the ease by whih the domain of that magentic layer would have to rotate) that would be needed to read data from dots as small as these would have to be tremendous, and it would have to be able to reliably distinguish between the magentic field of the dot it is reading and the fields of those dots only a few angstroms away. The problem with this is that to read magentic fields as weak as those generated by these tiny dotes, the domain of the magentic layer in the magnetoresistive head would have to rotate very easily (have low coercivity). When magentic domains have low coercivity it is difficult to keep them oriented in one direction, because heat from the atmosphere starts to become sufficent to rotate these domains on their own.

I'm not saying its not possible, I'm just saying that its a long way off.

Oh, and the article states somethign to the effect of: these researchers have created 5nm nickel dots, which are about 10 times smaller then those previously produced. It shouold read "those previously produced, by them." I personally worked on a project at the Naval Research Laboratory a number of years back where I used a reverse micelle synthesis technique to fabricate spherical 3 nm Iron Oxide (superparamagnetic) and 11nm FePt (ferromagnetic) nanoparticles. Further, the use of the reverse micelle technique to create magnetic nanoparticles on the scale asserted by these researchers has been known since the early 90's, and the potential use of these particles as memory has been around since the mid 90's as well. So to me there is nothing really new about wehat these guys have done.

I'm not trying ot sound arrogant, I'm just letting you know that this isn;t really new is all. Still interesting tech though.

TY for the input, I wish the article had given half that information. Doesn't sound like I will be backing up my important files on the first models. I think the likelyhood is the NT will be able to overcome it's technical issues in regards to this WELL before they work around the magnetic problems also at hand.

 

[Tab]

q]Originally posted by: klaviernista

Originally posted by: darfur

Originally posted by: darfur
Neat and all, but I thought that one problem with increasing the density of modern hard drives is that the magnetic fields created by all the little bits start to interfere with one another.

How is this any different at 10 times the density (well 10 times smaller anway)?

Anyone?

I examine patent applications for magentic media at the patent and trademark office. The problem you are describing has been around for a long time, as has so called "nanodot" media. This problem is called "intergranular exchange coupling" and contributes to increased noise in high density magentic media.

This problem arose as a result of the industry striving towards increased recording density. One way to get increased recording density is to reduce the size of the grains in magnetic layer (Basically, 1 grain=1 bit, so more grains =more bits per square inch). The problem with this is that as you reduce grain size, the coercivity (basically the strength by which a magnetic domain is held in a fixed direction) decreases. In other words, the orientation of each domain in each bit becomes more susceptible to being influenced by external magentic fields. Well, as each grain is magnetic and the coercivity of each grain is low at small grain sizes, the magnetic field of each grain impacts the orientation of the domain in each surrounding grain. As a result, the noise of the media is increased.

Industry has come up with a variety of ways to combat this problem. the most common way to prevent or reduce this type of coupling is to introduce Cr into the magnetic layer. Cr only has a certain solubilty in the crystalline lattice of a Co alloy (Co is the most common element used for the magentic layers in magentic media). When the CoCr magnetic layer is formed, it is first deposited (via sputtering or cvd) and then annealed. As a result of the annealing step, excess Cr segregates from within the crystalline grain into the area between adjacent grains (called the grain boundary). By controlling the amount of Cr which segregates, the spacing between grains is controlled. As you probably know, magnetic field intensity decreases as the distance from its origin increases. Thus, the influence of each grains magnetic field on surrounding grains is substantially reduced by the introduction of Cr into the grain boundary. In addition, non-magentic oxides such as SiO2 and TiO2 have also been used to segregate grains.

So, with nanodot media and quantum dot media, it is likely that some form of segregant will be utilized to separate each dot, or the dots themselves will be spaced apart when they are dposited so as to minimize this type of grain coupling. Many quantum dot media are formed by self assembly methods, so control over spacing between each dot can usually be controlled realtively easily.

Hope that helps. Probably more info then you wanted, but if you have more questions about magentic media let me know.

[/quote]

Just to make sure I understand this...

The smaller the grain the harder it is to keep the magnetic charge of the grain affected other grains... and is also more vunarable to external interruptions....

How is Cr stuff put onto a disc? As I understand it, it goes inbetween the layers of the grains and seperates them from each other and makes each grain less suspectable too changing each others charge...

We would also have to figure out how to make a read/write head that would be able to read and write onto something so small and would have to make very preciese readings...

Am I understanding this?

 

[klaviernista]

The smaller the grain the harder it is to keep the magnetic charge of the grain affected other grains... and is also more vunarable to external interruptions....

-Yes and no. Magnetic domains, while the consist of electrons oriented in particular directions are not typically referred to as charges. But otherwise I think you've got it. As the grain size goes down, the coercivity of each magnetic grain goes down as well. thus, each grains magnetic domain is more susceptible to interference from outside interference (external magentic fields) and temperature.

How is Cr stuff put onto a disc?

couple different ways. most often magnetic layers are depostited via sputtering from a target (basically, you hit a target (usually biased with an electric potential) with high energy particles/radiation, this kicks off tiny particles of the element/alloy from the target that you want to deposit, and then you slam those particles into a substrate you want to depoit on by guiding the particles to the substrate with a magentic or electric field). You can sputter form a single target (I.e. a target that is an alloy of cobalt and chromium) or you can co-sputter form multiple targets (i.e. a 1st target of Cobalt and a second target of Cr). If you use a single target the amount of Cr in the deposited thin film is determined by the target composition. If you use multiple targets the composition of the thin film is controlled by controlling the voltage applied to each target. You are forming an alloy film of Co and Cr no matter which of these two methods you use. You can also do this via chemical vapor deposition, but thats a complicated process that I will leave for a later discussion. Thats how Cr gets into the magentic layer.

As I understand it, it goes inbetween the layers of the grains and seperates them from each other and makes each grain less suspectable too changing each others charge...

-mostly correct. You said "goes in between the layers of the grains" which makes me think you might be confused about the strucutre of a alloy thin film. One basic way to think of it is like this: Imagine a table with a single 10X10X1 array of tennis balls on it (10 tennisballs in horizontal direction, 10 balls in vertical direction, 1 tennisball high. Now, imagine that array is ordered such that each tennisball is very close to the next one, but not touching. In this (very simplified) example, the table is the substrate. The tennisballs are individual grains of a metal layer that is depostied on the substrate. The spaces between the balls is the grain boundary. Note that for this example I assumed non-touching grains and a monolayer, in real life grains often touch and films are thousands of atomic layers thick.

Ok, back to your question: Cr in the magnetic layer segregates into the grain boundary when the film is annealed after deposition. The Cr in the grain boundary both shields adjacent grains for fields generated by other nearby grains, and attenuates the influence of these fields by increasing the distance between grains (magnetic flux decreases with distance from its origin)

We would also have to figure out how to make a read/write head that would be able to read and write onto something so small and would have to make very preciese readings...

-correct. It doesn't matter what the theoretical capacity fo a recording medium is. While media that can hold more stuff is always good, it doesn't mean squat if we have a media the size of a postage stamp that can hold all the information in the library of congress if we have no way of actually recording that data to the media and retrieving it in a reliable and speedy manner.

 

[Wahsapa]

this has probably been the single most informative post i'v ever read on anandtech
:thumbsup:

 

[klaviernista]

Thanks! Glad you found it interesting. Like I said, I examine recording media patent applications at the patent office, so i read about this stuff for about 6 hours a day. Glad to know its going to some use.