What is the meaning of 'pseudo-spin wave' in solid state physics?

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Discussion Overview

The discussion revolves around the term "pseudo-spin wave" in solid state physics, particularly in the context of phase transitions and collective excitations in materials like KDP (KH2PO4). Participants seek to clarify the meaning and implications of this term, exploring its relationship to established concepts such as spin waves and pseudo-spin in various systems.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about the term "pseudo-spin wave" and requests clarification.
  • Another participant emphasizes the importance of providing an exact citation for the term to understand its context better.
  • A participant mentions that in order-disorder systems, soft collective excitations are described as unstable pseudo-spin waves rather than phonons, but they seek further understanding of this distinction.
  • There is a suggestion to look into Bloch's theory of spin waves in ferromagnets to gain insight into related concepts.
  • A participant proposes that pseudo-spin may relate to a two-level system treated as a spin 1/2 system, where the evolution of a defined pseudo-spin operator could lead to pseudo-spin waves.
  • Concerns are raised about whether "pseudo-spin wave" is a misnomer for "magnons" or if it refers to "spinons," indicating ambiguity in the terminology.
  • A later reply provides examples of articles where the term "pseudo-spin wave" is used, suggesting that the terminology may draw parallels between ferroelectrics and ferromagnetism.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the meaning of "pseudo-spin wave," and multiple competing views and uncertainties remain regarding its definition and application.

Contextual Notes

The discussion highlights the need for precise definitions and context when using terms like "pseudo-spin wave," as different fields may apply similar terminology with varying meanings. There is also an indication that the term may not be well-documented in standard solid state physics literature.

oh1905
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Hi, I am not a physicist but a crystallographer. During I read a article I have found "Pseudo-spin wave", which I could not unterstand.
What dose it mean exactly?
Thanks in advance.
 
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oh1905 said:
Hi, I am not a physicist but a crystallographer. During I read a article I have found "Pseudo-spin wave", which I could not unterstand.
What dose it mean exactly?
Thanks in advance.

It would help if you make an EXACT citation to whatever it is you are reading. It gave the rest of us the ability to check the CONTEXT in which such terms are used. This is especially true in cases where the same terms are used to mean different things in different areas.

This advice applies to everyone who wants to know what so-and-so means from something they read.

Zz.
 
I read an article about a phase transition. There are generally two types of phase transition. It is said that in order - disorder systems, like KDP (KH2PO4), the soft collective excitation are not phonos but rather unstable pseudo-spin waves. But I don't understand what it means.
 
oh1905 said:
I read an article about a phase transition. There are generally two types of phase transition. It is said that in order - disorder systems, like KDP (KH2PO4), the soft collective excitation are not phonos but rather unstable pseudo-spin waves. But I don't understand what it means.


And I responded:

"It would help if you make an EXACT citation to whatever it is you are reading."

If you believe that what you have just told me qualifies as an exact citation, then I am unable to help you.

Zz.
 
oh1905, by exact citation, Zz means a reference to the article, including authors, journal, volume, page numbers and year.

Secondly, do you know what a spin-wave is ? Look for Bloch's theory of spin waves in ferromagnets (other spin waves are similar).

Next what you need is an understanding of pseudo-spin. As I'm not terribly familiar with this, I can't say much about it. The one context that I'm roughly aware of is in a 2-level system, you may choose to treat the system like a spin 1/2 system and define an operator that plays the role of Sz. This is your "pseudo-spin" operator and its evolution can give rise to pseudo-spin waves (I guess).
 
Gokul43201 said:
oh1905, by exact citation, Zz means a reference to the article, including authors, journal, volume, page numbers and year.

Secondly, do you know what a spin-wave is ? Look for Bloch's theory of spin waves in ferromagnets (other spin waves are similar).

Next what you need is an understanding of pseudo-spin. As I'm not terribly familiar with this, I can't say much about it. The one context that I'm roughly aware of is in a 2-level system, you may choose to treat the system like a spin 1/2 system and define an operator that plays the role of Sz. This is your "pseudo-spin" operator and its evolution can give rise to pseudo-spin waves (I guess).

The problem in responding to something this vague is that I have no clue if a "pseudo-spin wave" is really just a bad terminology being used to refer to "magnons", or if it is really referring to a loosely-defined "spinons", similar to the system you mentioned. I've seen papers making references to "spin waves" to either of them.

It is why I asked for an exact citation.

Zz.
 
ZapperZ said:
It is why I asked for an exact citation.

Zz.

I suspect the OP misunderstood what was meant by a citation.
 
For example, in the articles by Chen Jun et al 1988 J. Phys. C: Solid State Phys. 21 2255-2266 or T3 / 2 Contribution to the Specific Heat of Ferroelectrics at Low Temperatures by W. N. Lawless Phys. Rev. Lett. 36, 478–479 (1976), this terminology "pseudo-spin wave" is used. I guess, this terminology comes from spin-wave like the prefix "ferro" was borrowed form the field of ferromagnetism to take note of certain similarities of the properities of ferroelectrics and ferroelastics with those of ferromagnetics. But I could not find it in the books about solid state physics.
 

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