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Solid-state physics studies how macroscopic properties of solids (mechanical, electrical, optical, etc.) result from their microscopic structure. It usually deals with the scale where quantum properties of the particles are substantial.

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Why is the energy required to create an electron-hole pair in semiconductors higher than their band gap energy?

I am studying semiconductor physics and in more than one book I have found that the energy needed to create an electron-hole pair in Si and Ge is a few times higher than the band gap energy. For ...
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How is the product $L\cdot S$ between orbital and spin angular momentum operators defined? Do they act on the same or different Hilbert spaces?

For an electron, are the Hilbert spaces for the spin angular momentum and the orbital angular momentum the same or are they different? If they're different, how do we justify the operator $L\cdot S$ ...
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Understanding the fractional quantum Hall effect in Chern-Simons formalism described in Wen's book

So I study fractional quantum hall effect with Chern-Simons formalism by using Wen's book, this is an excellent book, but it assumes that you know field theory very well thus it has gaps between steps....
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activation of donors via annealing

I've been reading up on semiconductors and quantum computing in general and have come across "activating donors via annealing" a lot, in papers such as here for example. From what I gathered, they ...
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21 views

estimating number of electrons available for conduction [on hold]

I've been asked to estimate the number of electrons in a metal, and the number of electrons available for conduction. I don't want to use proper Fermi-Dirac or anything, I just want an easy way to ...
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1answer
76 views

Is there a finite number to the possible state of electron in an atom?

Okay, I know you may say, there are infinite numbers of possible state of an electron between its ground state and ionic state, since energy levels get continuous as electron gets farther away from ...
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34 views

How many electrons are in the $k$-space?

Let's assume we have a metal cube with edge length $L$ and in its volume $L^3$ are $N$ conduction electrons. The components of the wave vector are quantized. i.e. $k_x=m\cdot (2\pi/L)$ where $m=0,\pm ...
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What is it about metal elements that means their conduction and valence bands overlap, as opposed to non-metal elements where there is no overlap?

I can't see why metals have overlapping bands and a higher Fermi level compared to Non-metals where there is no overlap and the Fermi level is not in the conduction band.
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31 views

Mental contradiction: Valence electrons do not move at the non-zero wavevector?

I have a mental contradiction. Let's consider the following band structure with the Fermi energy somewhere inside the gap: where $\Gamma$ point represents the zero value of the wavevector $|\vec{k}|$....
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34 views

Why Pt-Ir Alloy or Tungsten is used for the tip in scanning tunneling microscopy?

Just want to know the properties which qualify these materials to be used as the same.
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How to determine the degree of how high a symmetry of high-symmetry points in the first Brillouin zone?

For exmple, we have a hexagonal lattice with hexagonal Brillouin zone, shown in the picture The points $\Gamma$, K, M and $\Lambda$ are high symmetry points. Now, $\Gamma$ point is the highest-...
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Resource for plasma oscillations and Plasmons

I want to learn the basics of classical Plasma oscillations and plasmons. But I have a very heuristic understanding of plasma oscillations that it is a collective oscillation of charged particles (e.g....
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27 views

Why does the Hall Coefficient not hold for certain metals?

We know metals have electrons as their main charge carriers, so we can arrive at the conclusion that $R_H$ is negative. $R_H=\frac{1}{q n}$, where $q$ is the charge of carriers, which is negative for ...
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2answers
55 views

What is the significance of the time $\hbar/E_F$ where $E_F$ is the Fermi energy?

For free electrons in a metal, the Fermi energy $E_F$ (defined as the highest filled energy level at $T=0$). It represents a characteristic energy scale of the system as well as the energy of the ...
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43 views

Simple diffraction on periodic structures

I am trying to understand diffraction on periodic structured in solid state physics. Q is the source of the spherical wave. R the vector to the object and R+r the vector to the scattering centre P, ...
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1answer
32 views

How do you calculate the density of free electron for alluminium and silicon? [closed]

How do you calculate the density of free electron for alluminium and silicon? For gold I have used the formula: $N=\dfrac{n\,\rho \,N_a}{A}$ where $n$ is the number of electron valence, $\rho$ is the ...
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27 views

How to calculate the emissivity of a metal from first principles?

I wonder how to calculate the emissivity of a metal (or a conductor if you prefer) starting from first principles. I.e. starting from a solid state physics model of a metal (for instance a Fermi gas ...
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1answer
44 views

Help me understand a little bit about this abstract

I was reading a story on phys.org: Holographic image of a black hole proposed in a graphene flake (Lisa Zyga, 25 July 2018, phys.org) From there I followed a link to the paper Quantum ...
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Can the melting temperature of metals be altered by modifying the local electric charge?

I'm researching a project in which metal needs to be melted. It would be very helpful to be able to reduce the melting temperature to improve the feasibility of the project. I've been looking into ...
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19 views

Calculating longitudinal sound velocity

I would like to calculate the longitudinal sound velocity in a solid state object. Specifically, I would like to derive the formula: $c^2 = \frac{\partial P}{\partial \rho}$. Starting from the ...
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2answers
158 views

What is(are) the effect(s) of disorder on electrical conductivity?

As a non-specialist, I asked the question "What are disorders in condensed matter parlance?" about the meaning of disorder in condensed matter physics. I also wrote a non-specialist answer after some ...
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3answers
53 views

Joul-heat melting of a metallic wrench - why is it so weird?

I found a video of a wrench that melts when put between two cables. The current is high and the wrench starts to heat-up and melt. But WHY does it heats up quickly near the cables connection points ...
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Bloch theorem in Hofstadter problem

right now I'm dealing with the Hofstadter Butterfly. Currently I'm reading and trying to understand a paper. It's about the following paper: https://arxiv.org/pdf/cond-mat/9312088.pdf. Zabrodin, ...
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1answer
34 views

Breaking translational invariance on a 1D periodic lattice

I am seeking some clarification on the process of breaking translational symmetry in a bosonic lattice by applying a uniform external magnetic field, which was stated as a fact in this paper: https://...
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1answer
67 views

Derivation of thermal conductivity of a solid body

I am reading a german physics book called "Festkörperphysik" written by Gross/Marx. And I came to following situation: $$\frac{d\langle n\rangle}{dt}=\frac{\partial\langle n \rangle}{\partial t}\...
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Bragg scattering off an array of wiggly lines

I'm currently working through some problems in Chaiken and Lubensky and I found that my understanding of scattering theory is weaker than I thought. So I could use a sanity check on this problem ...
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Cyclic Fatigue Testing Causing Increase in Spring Rate [closed]

Test parameters: 3.1mm spring cycled between 1.7mm and 1.4mm 10e6 times at 20hz (coil bind: 1.2mm) Before and after test spring load measured at 1.7mm and 1.4mm and calculated rate between these set-...
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1answer
28 views

Hermitian conjugate in Hubbard model hopping term

I'm new to Hubbard model and I have a few questions about it. From the sources I can find on the internet, Fermionic-Hubbard model is often written as (please correct me if I'm wrong!) \begin{align} H ...
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1answer
68 views

Reciprocal Lattice and Fourier Transforms

In David Tong's lecture(Application Of Quantum Mechanics) the second line of Fourier transform the integration over x ∈ R^3 is replaced by a summation over r ∈ Λ, together with a integration over ...
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24 views

How do I calculate the number of free electron in gold per square cm?

I am studying the paper Radial dose distribution in the delta-ray theory of track structure by F.Cucinotta, R.Katz, J.W.Wilson, R.R.Dubey (NB: PDF) In equation (6) page 248 there is a term $N$ which ...
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47 views

Switch from sum to integral in non-Cartesian coordinates

when I do the BZ integral in honeycomb lattice numerically I need to calculate: $$\left| {\begin{array}{*{20}{c}} {\frac{{\partial {k_x}}}{{\partial {{k'}_1}}}}&{\frac{{\partial {k_y}}}{{\partial {...
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1answer
80 views

In a material, how does the heat equation arise from phonons? And from electrons?

What would be the starting point to derive the heat equation in a material? Generally, in insulators the heat is mediated via phonons while in metals (conductors), electrons are the main responsible ...
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961 views

Two-dimensional electron gas

I'm studying solid-state physics and it says that if the solid is thin enough we can view it as a 2D solid but it doesn't say how thin it should be that the electrons are restricted in one dimension. ...
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1answer
70 views

Berry Phase for Bloch electrons

I am new to the topic of Berry phase. The definition says that Berry phase depends only on the path in the parameter space of $R$, where the Hamiltonian is $H(R)$, but whatever problems I have seen, ...
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The Hermicity of k.p Hamiltonian with operator ordering?

I am trying to use the k.p method to study quantum well band structure. One example Hamiltonian look like this [J. Appl. Phys., 116, 033709(2014)] []1 where ${{\hat k}_ \pm } = {{\hat k}_x} \pm i{{\...
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Bohm and Pines approximation in Plasmons Theory (RPA)

I am studying Plasmons on "H. Haken-Quantum Field Theory of Solids", and I'm arriving to this relation \begin{align*} i\hbar\frac{d}{dt} \left\langle\Phi\left| \hat{a}^{\dagger}_{\overrightarrow{k}+\...
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31 views

Analytic Microcavity Polariton Dispersion Relation

I feel like I have a good theoretical understanding of how one derives the microcavity polariton dispersion relation utilizing the rotating wave approximation, but when it comes to actually ...
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1answer
137 views

Is topological surface state always tangential to bulk bands?

Think of a topologically nontrivial $D$-dimensional system. Its bulk bands form a $D+1$-dimensional manifold ($+1$ from energy). Its surface/edge bands form a $D$-dimensional one. Is the latter always ...
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43 views

Time reversal of Bloch Hamiltonian (at TRIM points)

I know that time-reversal symmetry requires the Bloch Hamiltonian $H(\textbf{k})$ to transform as: $$ \Theta H(\textbf{k}) \Theta^{-1}=H(-\textbf{k}) $$ where $\Theta$ is the time-reversal operator. ...
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1answer
36 views

Parity of Bloch states at TRIM points

There is an argument presented in Fu and Kane's paper on inversion symmetric topological insulator which I have not yet convinced myself. Just below Eq.(3.6), the authors said that because of ...
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1answer
75 views

What happens when we add free electrons to an insulator?

I'm trying to understand why an insulator doesn't conduct electricity. If I understand correctly, the energies of electrons of an insulator are bound tightly to the nucleus, so there are no free ...
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How to identify the basis of a crystal?

I'm having some difficulty identifying, geometrically, the basis of crystals. I have two particular examples. The first one, CaF2, I know we have a Ca at (0,0,0) and 2F, one at (1/4, 1/4, 1/4) & ...
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1answer
34 views

Variational calculus and KKR method for band structure calculation

I’ve been studying the KKR method from the original Kohn and Kostoker’s paper (https://journals.aps.org/pr/abstract/10.1103/PhysRev.94.1111). On the text, they use variational calculus for dealing ...
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12 views

Electron scattering. Relation between thermal and electrical properties

Let's restrict to elastic electron phonon scattering in metallic periodic crystals. Is the scattering mechanism responsible for electronic thermal conductivity/resistivity the same as for electrical ...
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1answer
45 views

Does corrosion of metals depend on electron degeneracy pressure?

Corrosion is about losing electrons for the corroded metal and gaining electrons for the oxidising substance. Is it correct to assume that what controls this process is the electron degeneracy ...
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1answer
25 views

Why do Spin Density Waves form?

can someone tell me if there is an intuitive picture why electrons form Spin Density Waves (SDWs), if the charge density diverges? I know that in 1D there is a divergence in the electronic ...
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22 views

Graphene differential conductivity from the dispersion equation of electrons

In a exercise about monolayer graphene, after carrying several calculations, we come to the conclusion that the dispersion equation for the electrons is roughly linear : $E(k) = \pm \hbar v_f k$. ...
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97 views

Confusion regarding Hall effect in semiconductors

In many places, it's mentioned that in hall effect, the holes move under the influence of magnetic field in the direction as shown in the figure. In this figure itself, the bound electrons move in the ...
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The link between spin singlet and the emergent (heavy fermion) fermi liquid in Kondo physics

I have been trying to understand the Kondo physics. Based on Anderson model, at low temperature $T<T_\text{K}$, the local spin gets screened by the itinerant electrons with a formation of the spin ...
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Why do black bodies or black colored bodies cool down faster than white ones? [duplicate]

Recently, I found an exercise in which a graph was shown with the variation of temperature of two painted cans as they received sunlight. One of the questions was "Which of these two bodies will ...