Thursday, September 14, 2023

Listing mistakes in Condensed Matter Physics: A Very Short Introduction

Someone told me that the day after your book is published you will start finding errors. They were correct.

Here are the first errors I have become aware of.

On Page 2 I erroneously state that diamond "conducts electricity and heat very poorly."

However, the truth about conduction of heat is below, taken from the opening paragraph of this paper.

Diamond has the highest thermal conductivity, L, of any known bulk material. Room-temperature values of L for isotopically enriched diamond exceed 3000 W/m-K, more than an order of magnitude higher than common semiconductors such as silicon and germanium. In diamond, the strong bond stiffness and light atomic mass produce extremely high phonon frequencies and acoustic velocities. In addition, the phonon-phonon umklapp scattering around room temperature is unusually weak.

Figure 2 on page 4 has a typo. Diamond is "hard" not "hand".

On page 82 I erroneously state that for the superfluid transition, the "critical exponent alpha was determined to have a value of -0.0127, that is to five significant figures."  The value actually has three significant figures. 

I thank my engineering friend, Dave Winn, for pointing out the first and third errors.

Update. August 27, 2024.

On page 40, I erroneously state that shear sound waves exist in a liquid. I thank Jean-Noel Fuchs for pointing out this error. Below, I have drafted a corrected paragraph

"In a fluid (gas or liquid) one way to distort a cubic volume of the fluid is to compress the cube into a shape (a rectangular prism) where the lengths of the sides are not identical, but the angles between the sides of the shape are still 90 degrees. Sound waves in air consist of this type of compression: oscillations in the density and pressure of the air occur in the same direction that the sound wave travels. 

      In an isotropic solid there is a second type of distortion: the shape of the cube is changed to that of a rhombohedron, the angles are no longer 90 degrees, but the lengths of the sides remain the same. Associated with these two types of distortions, there are two distinct ways in which sound can travel through a solid. A second type of sound wave corresponds to the second type of distortion, and is called a shear wave. The two types of sound travel at different speeds. An earthquake produces both types of waves: pressure waves and shear waves, the latter travelling slower. Observing and comparing the two types of waves plays an important role in seismology and in the detection of earthquakes."

There are some subtle issues here that go beyond what is appropriate in a VSI. Damped shear waves can exist in a liquid for wavevectors larger than some critical value. I will discuss the issues in a separate blogpost.

Please do write other errors in the comments below. This will help with future revisions.

5 comments:

  1. Hi Ross, I preface this by saying do take this with a shovel of salt as I am only a PhD student. Basically I liked your book quite a lot, but I am a little confused as to why the superconducting dome is centered on a hole concentration of 0.15 as most similar figures have it optimally doped at 0.2 or a bit less than that.

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    1. I should say the figure I am asking about is 23.

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    2. As I was just expecting it to be more like this although this is all very semantics as like I do not think moving the dome a few 0.1's really matters https://www.nature.com/articles/nature14165/figures/2

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    3. There is no universal phase diagram for the cuprates. The location of the maximum superconducting Tc can vary between classes of materials. Moreover, for the pseudogap, the phase boundary is not well defined, being different depending on what experimental probe one uses to define it. Hope that helps.

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  2. Ah thanks for clarifying that Ross, I did not realise the optimal doping concentration and pseudogap boundary changed so much for the cuprates depending on the class. Out of curiosity what is your interpretation at present of what the pseudogap's connection with the superconducting phase is if any? As I know some people thought it was some almost premature sort of pairing but from Steve Kivelson's talks he strongly disagrees with that interpretation. Thanks

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