DOS for impurities in a dielectric

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Discussion Overview

The discussion revolves around calculating the density of states (DOS) for ferromagnetic impurities, specifically rare-earth ions, implanted in a dielectric material. The focus is on the theoretical framework and methodologies applicable to this scenario, considering the weak interactions between the ions and their response to an external magnetic field.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant inquires about calculating the DOS for ferromagnetic rare-earth ions in a dielectric, noting the high concentration of ions and their weak interactions.
  • Another participant questions the characterization of the ions as ferromagnetic if they are non-interacting, suggesting they may be paramagnetic instead, and recommends looking into crystal field theory for further insights.
  • A clarification is provided by the original poster, indicating that the ions originate from a ferromagnetic rare-earth metal but may not exhibit magnetic ordering due to their dilute concentration in the dielectric.
  • A suggestion is made to explore existing literature, mentioning specific salts used in related studies and noting that collective effects in these materials are often weak.
  • The original poster expresses gratitude for the reference provided and indicates an intention to review it amidst other commitments.

Areas of Agreement / Disagreement

Participants exhibit some confusion regarding the magnetic properties of the ions, with differing interpretations of their ferromagnetic nature versus paramagnetism. There is no consensus on the implications of the ions' interactions or the appropriate theoretical approach to calculating the DOS.

Contextual Notes

Participants acknowledge limitations in their understanding of the interactions and properties of the ions, particularly regarding the influence of the dielectric and the potential for magnetic ordering.

Who May Find This Useful

This discussion may be of interest to researchers and students working on magnetism in dielectrics, those studying rare-earth materials, or individuals exploring theoretical approaches to density of states calculations in disordered systems.

f95toli
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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)
 
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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.
 
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.
 
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
 
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)
 

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