# DOS for impurities in a dielectric

1. Jun 16, 2014

### f95toli

I have a question regarind how to calculate the DOS for ferromagnetic impurities in a dielectric

We have samples with ferromagnetic rare-earth ions implanted in a dielectric material. The concentration known and is quite high but the ions are probably only interacting weakly (they are on average about 10nm apart).These ions can interact with an external field (which does not affect the dielectric).

I now need to calculate the DOS of the ions interacting with the field. However, I do not even know where to start (possibly because I haven't done anything like this in >15 years).

I believe the interactions are a bit too weak for it to be considered a spin glass. However, the usual theory for disordered glasses should apply.

Any ideas for where to start? Presumably it should be calculable since I know the concentration and the properties of the ions (and they are not interacting)

2. Jun 16, 2014

### DrDu

I am a little bit confused: If the ions are non-interacting, how can they be ferromagnetic? I suppose you mean paramagnetic at best.
The f-levels of the ions should hardly be influenced by the dielectric. I would look out for crystal field theory to calculate the splitting.
If you know some German, the book "Einführung in die Festkörperphysik" by K.-H. Hellwege may prove useful as it contains lots of stuff on lanthanide magnetism.

3. Jun 17, 2014

### f95toli

Sorry, I wasn't thinking when I wrote that:shy:
What I meant was that the ions come from a rare-earth metal which is ferromagnetic; but if the ions in the dielectric are dilute enough there shouldn't be any magnetic ordering(although we are not quite sure)

My German is rusty (to say the least) but I will see if I can find that book.

4. Jun 17, 2014

### DrDu

There should be plenty of stuff around.
E.g., salts like Gadolinium sulphate octahydrate have been used extensively in adiabatic demagnetization.
Even in these salts, collective effects are often weak.
Oldies but goldies:
http://www.dtic.mil/dtic/tr/fulltext/u2/a122791.pdf

5. Jun 17, 2014

### f95toli

Thanks
That reference looks very useful, I will try to read it this week (once I've finished about two days worth of non-physics-related paperwork:yuck:)