Friday, March 29, 2024

Thoughts on undergrad solid-state content

Figuring out what to include in an undergraduate introduction to solid-state physics course is always a challenge.   Books like the present incarnation of Kittel are overstuffed with more content than can readily fit in a one-semester course, and because that book has grown organically from edition to edition, it's organizationally not the most pedagogical.  I'm a big fan of and have been teaching from my friend Steve Simon's Oxford Solid State Basics, which is great but a bit short for a (US) one-semester class.  Prof. Simon is interested in collecting opinions on what other topics would be good to include in a hypothetical second edition or second volume, and we thought that crowdsourcing it to this blog's readership could be fun.  As food for thought, some possibilities that occurred to me were:

  • A slightly longer discussion of field-effect transistors, since they're the basis for so much modern technology
  • A chapter or two on materials of reduced dimensionality (2D electron gas, 1D quantum wires, quantum point contacts, quantum dots; graphene and other 2D materials)
  • A discussion of fermiology (Shubnikov-DeHaas, DeHaas-van Alphen) - this is in Kittel, but it's difficult to explain in an accessible way
  • An introduction to the quantum Hall effect
  • Some mention of topology (anomalous velocity?  Berry connection?)
  • An intro to superconductivity (though without second quantization and the gap equation, this ends up being phenomenology)
  • Some discussion of Ginzburg-Landau treatment of phase transitions (though I tend to think of that as a topic for a statistical/thermal physics course)
  • An intro to Fermi liquid theory
  • Some additional discussion of electronic structure methods beyond the tight binding and nearly-free electron approaches in the present book (Wannier functions, an intro to density functional theory)
What do people think about this?

27 comments:

  1. Ryan Comes9:44 PM

    Copying from my Twitter reply in case you want everything to be in one spot later...

    When I taught that course I let students vote at the end of the semester for the last week. Superconductivity won, but you're right that it's necessarily high level. Fermi surfaces also look like they're lacking based on the TOC, so I'd vote fermiology as well.

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  2. Solid state platforms for quantum information are another good area.

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    Replies
    1. Also, glasses and disordered/amorphous materials are another worthwhile topic.

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  3. Anonymous4:23 AM

    If you could include a small introduction of topology it would be very nice.

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  4. Hi Anonymous: There are a lot of ways into topology. SSH chain is a standard one, but somehow that always leaves me kind of bored. Integer quantum Hall, Berry phase and anomalous velocity are both mentioned above. Do you have some particular avenue that you are interested in?

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  5. When I teach solid state I supplement Steve's book with discussions of graphene, Berry curvature, anomalous velocity, Chern number, and topological semimetals.

    (my lecture notes are here if you're curious: https://u.osu.edu/skinner-352/)

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  6. Thanks Brian, these are really nice!

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  7. Anonymous4:31 PM

    A section on applying magnetic field on a lattice, (in the tight binding model) with a glimpse of gauge fields would be nice.

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  8. Anonymous7:18 PM

    I have been visiting graduate schools and every time I talked with other CMT students and professors, they mention density functional theory. So, I would vote on that...

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  9. Peierls substitution! Good point. No one ever covers this and they should!

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  10. sauravk9253:10 AM

    Another thing that would be nice is a discussion on symmetries, specifically Time reversal, particle-hole and sub-lattice symmetries and their actions on the Bloch Hamiltonian. May be some lattice symmetries as well.

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  11. Hi Sauravk: Time reversal is probably a good one. I assume by p-h you mean superconductors -- the problem there is that it presupposes some knowledge of superconductors. The issue with lattice symmetries is that it kind of requires group theory --- although perhaps some mild version of this might be done without all of the machinery. Maybe just look at inversion?

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  12. Anonymous4:27 AM

    I feel like many of the suggestions above are certainly interesting for students who want to pursue a career in research and/or to get talented students interested in taking advanced CMP courses. When deciding on the syllabus of an introductory solid state physics course, one should always keep in mind that this may be the only solid state physics course that some students take before graduating and taking a job in industry, however. As someone who was working in academia (CMT) for an extensive period of time and who switched to industry a while ago, I have the impression that quite a few fresh physics graduates miss some fundamental concepts and basics of solid state physics that would be very benefitial when pursuing a career in industry. Specifically, semiconductor physics is definitely covered way too superficially in most introductory solid state courses. Apart from that, I‘d suggest to put a bit more emphasis on basic concepts such as quasiparticles, this I’d vote for Fermi liquid theory. Also, a short chapter on transport (Drude, Boltzmann equ.) shouldn‘t be missing in an intro course, imho.

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  13. Anonymous6:16 AM

    How about topics in other ways of knowing, such as the indigenous viewpoint on material properties? I think a foreword with a heartfelt apology and a trigger warning for the white, patriarchal, and Eurocentric viewpoints perpetuated in the book would be appropriate.

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  14. Anonymous7:19 PM

    In response to Anon 4:17 AM, I agree with the need to teach more semiconductor physics. Perhaps one way to bridge the gap for physics undergrads would be to offer a 2-3 week short course that EE departments can offer to students who have taken solid state physics already.

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  15. Anonymous10:41 AM

    In response to Anon 7:19 PM

    Any textbook suggestions for a semicon physics focused course? Right now I teach a Device Physics and Microfab course, but our students seem a bit behind on the semiconductor physics basics for some of this - right now I'm torn between using Chenming Hu's book (Modern Semiconductor Devices for Integrated Circuits) and Streetman + Banerjee's Solid State Electronic Devices, which works fine, but I'm open to suggestions as well.

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  16. Anonymous11:39 AM

    In response to Anon@4:27AM and Anon@7:19P
    Could you expand on which semiconductor physics topics you think would be most useful to cover more deeply?

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    Replies
    1. Anonymous12:06 PM

      I think a basic overview of band diagrams and a discussion of MOS and pn junctions is useful. My thought is that physics grads who wish to go into the semiconductor industry can benefit from a brief overview.

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    2. Anonymous4:42 PM

      The book is Sze. Old, but solid.

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  17. My favourite intro SS book is Hook & Hall 2nd Ed (Manchester Physics Series).

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  18. Hi Anonymous, thanks for the recommendation. I'd be interested to see what people teach that is beyond what is in Solid State basics. I do basic pn, basic MOSFET, and (very) briefly mention LED. If I were to write one more chapter (but not much more than one more chapter), what should semicond physics should go into it (keeping it at undegrad level). Thanks!

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  19. Xirtam Esrevni2:11 PM

    Curious why using second quantization formalism when introducing SC is not suitable? Are undergraduate quantum mechanics courses curriculum's not teaching 2nd quantization? Seems like things are out-dated if we aren't do so, especially with all the interest/attention in quantum computing.

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  20. Hi Steve, Regarding semiconductors one aspect of great practical importance that I would suggest to include is the temperature dependence of the carrier density in extrinsic semiconductors, i.e. the intrinsic range, the saturation range and the freeze out range (Ashcroft & Mermin, Fig 28.13).

    Two of the chapters on magnetism (20 and 21) feel a bit "thin" and could usefully supplemented with e.g. considerations on symmetries (this could also be a separate chapter/appendix touching on crystallographic symmetries), Landau theory, crystal-field and spin-orbit interactions and perhaps also the illustrative Stoner-Wohlfart model. Finally, I think it would be useful to expand the concluding section of chapter 15 to more clearly illustrate how Bloch's theorem is useful.

    I would look forward to a new version of your excellent book, and even more to a volume two.


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  22. I would like to see something about crystal symmetry in the curriculum. Most solid state physicists see to find it easier seem to find it easier to invent a new pseudoparticle than to understand how symmetry breaking, e.g. cubic -> tetragonal, removes degeneracies and introduces new modes of excitation.

    I know this might tread on to the toes of materials science, but octahedral symmetry groups are often not present and where the really interesting phenomena occur.

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  23. @Xirtam. I think in most places (certainly at oxford) most people believe that second quantization is at least masters level. While most first year quantum courses do cover raising and lowering operators at the level of the harmonic oscillator (and this gets you close to phonons I suppose), they certainly don't do this for fermions. I agree it isn't hard, but I think if an undergrad solid state textbook tried to use this it would quickly be declared to not be appropriate for undergraduates. But perhaps one has to make an exception for handling BCS theory which is a mess if you insist on not going second quantized.

    @NBC. There is already a very brief discussion of the temperature ranges for seminconductors (see chap 17). But yes, this could be expanded a bit.

    @NBC and @JonB. Symmetries! I do want to do this, but it is really challenging. I agree that this is important, but I'm a bit unsure how to handle it without at least a bit of group theory. I'm still thinking about it, but it is one of those things (kind of like superconductivity) where I feel that trying to do a cartoon-level discussion is so unsatisfying -- but trying to do it for real requires quite a lot of machinery.

    Thank you all for the ideas and the input! (This will be slow to develop I'm sure... but hopefully will get there!)

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  24. As a physicist working in engineering, I have a gigantic gap in metallurgy and materials science. For an intro course in solid state, it would be nice to have a little bit about why alloys do the things they do. What makes steel different than iron? Why do composites work?

    For a physics text, I would think the emphasis should not be on the zillions of different kinds of stainless steel, but on the principles behind them: why it's advantageous to alter the crystal structures in various ways, how fiber bonding creates strength, etc.

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