Introduction and motivation

In an effort to get more content on Tildes, I want to try and give an introduction on several 'hot topics' in semiconductor physics at a level understandable to laypeople (high school level physics background). Making physics accessible to laypeople is a much discussed topic at universities. It can be very hard to translate the professional terms into a language understandable by people outside the field. So I will take this opportunity to challenge myself to (hopefully) create an understandable introduction to interesting topics in modern physics. To this end, I will take liberties in explaining things, and not always go for full scientific accuracy, while hopefully still getting the core concepts across. If a more in-depth explanation is wanted, please ask in the comments and I will do my best to answer.

Today's topic

I will start this series with an introduction to spintronics and spin transistors.

What is spintronics?

Spintronics is named in analogy to electronics. In electronics, the flow of current (consisting of electrons) is studied. Each electron has an electric charge, and by pulling at this charge we can move electrons through wires, transistors, creating modern electronics. Spintronics also studies the flow of electrons, but it uses another property of the electrons, spin, to create new kinds of transistors.

What are transistors?

Transistors are small electronic devices that act as an on-off switch for current. We can flip this on-off switch by sending a signal to the transistor, so that the current will flow. Transistors are the basis for all computers and as such are used very widely in modern life.

What is spin?

Spin arises from quantum mechanics. However, for the purpose of explaining spin transistors we can think of an electron's spin as a bar magnet. Each electron can be thought of as a bar magnet that will align itself to a nearby magnetic field. Think of it as a compass (the electron) aligning itself to a fridge magnet when it's held near the compass.

What are spin transistors and how do they work?

Spin transistors are a type of transistor whose on-off switch is created by magnets. We take two bar magnets, whose north poles are pointed in the same way, and put them next to each other, leaving a small gap between them. This gap is filled with a material through which the electrons can move. Now we connect wires to the big bar magnets and let current (electrons!) flow through both magnets, via the gap. When the electrons go through the first magnet, their internal magnets will align themselves to the big bar magnet. However, once they are in the gap the electrons' internal magnets will start rotating and no longer point in the same direction as the big bar magnets. So that when the electrons arrive at the second magnet, they will be repelled just like when you try to push the north poles of two magnets together. This means the current will not flow, and the device is off! So, how do we get it to turn on?

By exposing the gap to an electric field, we can control the amount of rotation the electrons experience (this is called the Rashba effect). If we change the strength of this electric field so that the electrons will make exactly one full rotation while crossing the gap, then by the time they reach the second big bar magnet they will once again be pointing in the right direction. Now the electrons are able to move through the second big bar magnet, and out its other end. So by turning this electric field on, the spin transistor will let current flow, and if we turn the electric field off, no current will flow. We have created an on-off switch using magnets and spin!

That's cool, but why go through the effort of doing this when we have perfectly fine electronics already?

The process of switching between the on and off states of these spin transistors is a lot more energy efficient than with regular transistors. These types of transistors leak a lot less too. Normal transistors will leak, meaning that a small amount of current will go through even when the transistor is off. With spin transistors, this leak is a lot smaller. This once again improves the energy efficiency of these devices. So in short, spin transistors will make your computer more energy efficient. This type of transistor can also be made smaller than normal transistors, which leads to more powerful computers.

Feedback and interest

As I mentioned, I wrote this post as a challenge to myself to explain modern physics to laypeople. Please let me know where I succeeded and where I failed. Also let me know if you like this type of content and if I should continue posting other similar topics in the same format.

Mine is Epica - The Divine Conspiracy, been listening to it every day for the past week as I fall asleep. You might not think metal works as sleep-music, but it does for me haha :)

Here's a song off of the album https://www.youtube.com/watch?v=fRR-eLW1lXw

been sitting on two of these most of the day, might be a little messy.

i feel like it's a little stale since i left it waiting, and i'm significantly more sober than when i usually write.

as always, comments welcome. or ignore this entirely if you're not feeling it<3

bless.

bishop

also this one gets somewhat graphic, gonna start leaving these trigger warnings up top - drugs, alcohol, suicide, covers it i think, let me know if i should add anything else

been smoking and drinking
just so i can cope
gave her the ring
she put me on the ropes
new girl show up but
i don't got no hope
my heart is still sinking
i'm trying to float like

Gretel, baby, where did you go?
no crumbs left I can throw
Hansel in the forest alone
put me out of house and my home
hands full of green and some blow
no drinks left but the coke
she's laughing now - am I the joke?
turned my heartthrob into a stroke -

your bedside's left wide
open to the moonlight
head high, red eye
stranded on the roadside
you kissed, i cried,
while i watched papaw die
No sleep, four nights
you told me it's alright
helped me keep my head high
helped me say my goodbyes
then you hit me blindside
didn't get a goodbye

peace, bye, next flight,
right into his arms like
you've been biding time,
waiting for the day to strike me

down.

down.

down.

Left me tied strapped to the bed
Headphones looping what you said
Promises we could stay friends.
Cool ones pour down my head
I know the river Styx runs red
Little siren told me "Baby, dive in"
Closed eyes, woke up dead.
Didn't know God's a raven.

Now you got your Raybans
and your black Timbs
Got your new Amex,
one in the black print
Hope it was worth it
on your conscience
that you lied through your teeth
and he fucking lost it

costless

Must be nice right?
If it's not on the bill
it don't have a price
Fuck being nice,
Fuck doing what's right,
What's another sad white
boy taking his life?

Masochistic statistic
when his legs kick
Fuck vacation,
Miami,
Fuck a new chick
Cool one rain straight
to the forehead
Gorgeous.
One less problem
to deal with. Lord, yes.

Gretel, baby, where did you go?
no crumbs left I can throw
Hansel in the forest alone
put me out of house and my home
hands full of green and some blow
no drinks left but the coke
she's laughing now - am I the joke?
turned my heartthrob into a stroke -

Frozen chicken wings, about $5 a pound at the local Winco. Defrosted half in the microwave for about 5 minutes. Rubbed on Olive oil, threw in the air fryer for about 30 minutes at 400 degrees (f). Sprinkled on Tumeric, Paprika, garlic powder, onion powder, salt, pepper.

Holy shit is this good.

I just realized that I completely glossed over this week's programming challenge. For this week, let's do something more flexible: write a program that accepts a file as input--either through a file name/path or through standard input--and perform any form of analysis you want on its contents. That's it!

For instance, you could count the occurrences of each word and find the most common ones, or you could determine the average sentence length, or the average unique words per sentence. You could even perform an analysis on changes in words and sentence structure over time (could be useful for e.g. poetry where metre may play an important role). You can stick with simple numbers or dive right into the grittiest forms of textual analysis currently available. You could output raw text or even a graphical representation. You could even do a bit of everything!

How simple or complex your solution ends up being is completely up to you, but I encourage you to challenge yourself by e.g. learning a new language or about different textual analysis techniques, or by focusing on code quality rather than complexity, or even by taking a completely different approach to the problem than you ordinarily would. There are a lot of learning opportunities available here.

Personally, I hope it takes over Reddit’s role of being primarily for discussion and a place to congregate interesting content, staying away from the more mainstream-y aspects, like the redesign. What do you expect/hope for?

Hello there!

I just received my invite a few minutes ago and I'm happily exploring the site right now.
As many others, I came over from Reddit looking for a better alternative.
I tried to find some information about the current guidelines but wasn't really able to find anything of substance.

Apart from being civil with each other, what's the official ruleset and how can we as testers contribute?

Or whatever else you'd want to talk about concerning comic books!

A new comic book shop has opened in my town, and my fiancée and I are pretty excited about it. We've never really been into them, but we're pretty excited to get into them. On that note, does anyone have any good recommendations for a newcomer?

As a neat aside, we have a thirty-plus year old comic book-ization of Return of the Jedi, and that's pretty cool.