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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Ohm's Law: Drude Model

For a very long time now, I've been thinking about the Drude Model derivation of Ohm's Law. I know that a rigorous derivation requires a Quantum Mechanical approach. However, the mere fact that the ...
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264 views

How many of the 230 crystallographic groups are realized in nature?

All of them or only a subset? This is a famous and fundamental result in solid state physics.
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Correlation in electron gas

In the textbooks that I read (namely Ashcroft/Mermin , Marder, etc.) it seems that a distinction is made between the correlations in electron gas and a Couloumb interaction between the electrons. What ...
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25 views

Schottky Barrier - Why energy band levels at interface are assumed to remain the same that bulk

I have been chewing up some time ago the Schottky-Mott theory of Schottky Barrier height (which ignores the surface states). All the deduction seems to ground on fundamental thermodynamical principles ...
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P-N junction voltage under polarization

All the books that deal with the p-n junction under applied bias asume that the same equations used for the equilibrium case (no bias) can be used for the biased case provided that the juntcion ...
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1answer
22 views

Thomas - Fermi screening

I read in Ashcroft & Mermin's Solid State text that for the Thomas-Fermi approximation to be applicable, the external potential needs to be "slowly varying," What does it mean for a function (in ...
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59 views

Temperature in a Voltaic Cell

The potential difference across a voltaic cell varies with temperature. But my question is whether the voltage increases or decreases as temperature rises. According to the Nernst equation, the two ...
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94 views

Fermi Energy Variation

What would be a good Internet link that would properly explain Fermi Energy? How does the Fermi Energy of a material vary with external influence, such as doping of the material, and applied ...
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1answer
88 views

Is carrier charge density and carrier mobility constant in a given material?

If we assume the semi-conductor is doped by a variable amount, is there some way I can look up carrier charge density for the material in a reference somewhere? What about carrier mobility?
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137 views

I don't get band structure of solids

If the energy levels of bound electrons are discrete, why do band structures in solids arise?
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169 views

Is it more efficient to stack two Peltier modules or to set them side by side?

Is it more efficient to stack two Peltier modules or to set them side by side? And why? I have a small box that I want to cool down about 20 K below ambient -- cold, but not below freezing. (I want ...
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73 views

Kronig-Penney model

I am studying the Kronig-Penney model as treated in the book by Kittel: Introduction to Solid State Physics. In this model one considers a period potential which is zero in the region $[0,a]$ ...
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Real and imaginary parts of dielectric constant vs refractive index?

So for a complex dielectric constant $\epsilon = \epsilon_a + i\epsilon_b$, the wave vector and index of refraction are related to it through $k = \frac{\omega}{c}n$ and $n = \sqrt{\frac{\mu ...
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23 views

Microscopic definition/expression of/for the heat current

Often I see the following microscopic definition/expression of/for a heat current due to an external field $$ {\bf j}_Q = 2 \int \frac{\text{d}{\bf k}}{(2\pi)^3} \frac{\hbar {\bf k}}{m} ...
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200 views

Distinguishable, Indistinguishable Paramagnetic Ideal Gas

In the canonical ensemble, the partition function for an ideal gas is given by: $$\frac{Z}{N!}$$ The factor $N!$ accounts for the indistinguishability of the particles of the ideal gas. What ...
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52 views

Coulomb potential in atoms other than hydrogen

The energy of an electron on $H$ atom is given by the formula: $-13.6 \; \text{eV}/n^2$. The constant value is born from $H$ dielectric constant and efective mass of the electron. My question is: ...
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28 views

How does the color of fine dispersed metal particles change between silver and black?

Small dispersed particles of metals are often black, while a solid object of the same material would be some shade of silver. The most notable example is the use of metallic silver as the black color ...
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62 views

What does “optical conductivity” mean?

Does it just mean "AC electric conductivity"? If so, why have a special name for it, and why mention optical specifically? The wikipedia page on it is very sparse. This (warning, PDF) document just ...
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30 views

Zero band gap semiconductors

It is known that graphene is a zero band gap semi metal. It originates from the meeting of the linearly dispersed valence and conduction bands on the Fermi level at the same high symmetry point "K", ...
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82 views

Does Saturation velocity in semiconductors have a relation with the wavelength in which the peak in the absorption spectrum occurs?

Saturation velocity is the maximum velocity a charge carrier in a semiconductor, generally an electron, attains in the presence of very high electric fields. (source) I want to know if the ...
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47 views

Sold-State Band Structure - connection between Fermi Energy, Fermi Level and Work Fuction

I've been struggling with the concepts of these three terms - Fermi Energy, Fermi Level and work fuction. Now, I was given these definitions (in the context of semi-conductors): Fermi Level is the ...
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1answer
47 views

How does band gap vary with the cell volume?

How does band gap vary with the cell volume? is there a relation? If the volume is compressed, the interaction between atoms would be more, therefore the perturbation is higher hence the splitting ...
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1answer
56 views

Why can't a dislocation terminate in the bulk?

We are told that they can only terminate on surfaces, grain boundaries or other dislocations but we are not told why they can't terminate inside the crystal.
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125 views

Do indirect optical transitions “cool” the material a little?

So I'm reading in Ashcroft and Mermin about indirect optical transitions: So, a photon comes in, and it only excites the electron across the indirect band gap if a phonon with the appropriate wave ...
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74 views

Why is effective mass of holes positive?

i am trying to understand this. I know that the effective mass of electrons or holes is calculated as: $$m^* = \frac{h^2}{(4\pi^2)\frac{d^2E}{dk^2}}$$ Now,if i look at this plot for example: I ...
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89 views

Is diffraction through an aperture similar to diffraction by a plane of atoms?

I'm asking because I have a problem asking me what the diffraction pattern would be if instead of spherical atoms I'd have triangular atoms. I can't find anything about this in my X-ray diffraction ...
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Why can we allow the speed of light being infinite in case of Surface Plasmons?

I have a problem with understanding of these sentences: We have indicated in the opening paragraph of the Introduction that surface plasmon polaritons are solutions of Maxwell’s equations in ...
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214 views

How do the effects of semiconductor doping affect the Hall effect?

For instance, consider number 4 and 5 in the following sample: Using the right hand rule, B points downwards, conventional current points to the right (because of the 5V battery), and therefore, ...
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Why is the Hubbard model written down so late?

It is just the tight binding model plus on-site interaction. What prevented people from arriving at the Hubbard model?
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41 views

On the lattice structures of graphite

My question is the following: What causes graphite to have either a cubic lattice structure or a hexagonal lattice structure? Does it depend on how it is grown? Or is it a random process? I would ...
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1answer
20 views

simple pores make ceramic opaque

I want to know how a ceramic transparency is mostly affected by the pores, grain boundary, second phases etc. present inside of it, but the major contribution is due to the pores. Let's consider the ...
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1answer
128 views

Does the Bohr van Leeuwen Theorem also apply to ferromagnetism?

I know that the Bohr-van Leeuwen theorem shows that there could be not consistent pure classical explanation of dia- and paramagnetism. Does the same theorem also rule out a consistent classical ...
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83 views

Optical mode leakage through a layer of gold

The geometry of my semiconductor device is given below. The blue regions are gold, the grey ones - gallium arsenide (n-doped to $2.9 \times 10^{15} \mathrm{cm^{-3}}$). The dimensions are μm, i.e. it ...
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1answer
24 views

Why do we still get sharp scattering spots with quasi-crystal?

In a quasi-crystal, there is no translational invariance. This means there is no delta-function in the Fourier transform. But to get a sharp scattering spot, we need a delta function. Physically, ...
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66 views

What is the significance of the difference in the eigenvalue equations of Bloch functions for electrons vs photons?

any text on photonic crystals will highlight the almost perfect analogy between electrons in a periodic potential and photons in a periodic dielectric. The analogies are: $$V(\vec r + \vec R) = ...
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36 views

Are there any electro-optic crystals that are also pyroelectric but not birefringent?

As the title says, a crystal that is electr-optic and pyroelectric can it be non-birefrigent?
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Is an object's color/shine/texture dependent on its electrons only? If electrons are same then why are there so many different colors?

when we look at an object be it a metal or a non-metal are we looking at its electrons only, so then if all electrons are same then why do different chemicals or elements or objects have different ...
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1answer
143 views

Why does the Fermi Surface cross the Brillouin zone boundary at right angles?

I'm not sure why the fermi surface crosses the Brillouin zone boundary at right angles. I understand that this is normally the case, but not necessarily always. I'm aware that the fermi surface is a ...
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91 views

Why is an optical magnon with k=0 not an eigenenergy state?

I found in a paper the following explanation. Unfortunately, I can't understand it. Can anyone help me on this? In the limit of equal spins an optical magnon with k=0 gets an acoustical one at the ...
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264 views

What is crystal field anisotropy or effect ? It forces the magnetic moment to point in particular local direction..

Can you give a basic explanation of what is crystal field anisotropy ? What is the reason to arise ? In spin ice it forces the dipoles to point in the local 111 direction. For partially filled rare ...
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Physical, intuitive reason for divergence of dielectric constant at electronic percolation transition?

Several papers such as this (warning, PDF) and this (PDF again) talk about how, near the electronic percolation transition for a metallic 2D film, the real part of the dielectric constant diverges ...
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81 views

How to get conductivity from Green function $\mathcal{G}(x_1,x_2,\tau)$ of inhomogeneous system?

I'd like to study an inhomogeneous system, i.e., momentum is not a good quantum number therein. Therefore, I tried to calculate temperature Green functions like $\mathcal{G}(x_1,x_2;\tau)$, or its ...
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19 views

Why a multilayer OLED is generally more efficient than a single layer OLED?

Could anyone give me a brief explanation why multilayer OLEDS as more efficient than single layer OLEDs? What other advantages exist for multilayer OLEDs over single layer OLEDs?
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1answer
110 views

In a positively biaed PN junction, where do the injection carriers come from?

I am not quite understand i-v character of PN-junction diode. Here is the model in textbook. The PN junction diode can be divided into three regions. They are One depletion region near the PN ...
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Bragg diffraction and lattice planes

Crystalline substances show, for certain sharply defined wavelength and incident directions, very sharp peaks of scattered X-ray radiation. From the illustration below we see that we get constructive ...
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1answer
16 views

Extrinsic Photoconductor Charge Carriers

I'm studying some materials on semiconductors, and a section on photoconductivity has left me somewhat confused. In an extrinsic material, is photoconductivity the result of electrons moving from the ...
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1answer
67 views

Atomic nearest neighbor notation

I recently got a correction to a paper that I am writing. The correction references a section in which I talk about nearest neighbors. The comment says: Do you mean NN, NNN, etc., or NN, 2NN, 3NN? ...
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1answer
136 views

Adiabatic approximation

The adiabatic approximation for solid state systems is rather radical. I was wondering in which cases it breaks down. As it is based on the idea of the nuclii being much heavier than the electrons I ...
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1answer
55 views

Is the ferromagnetism of iron understood completely?

In Feynman's lecture notes, he said that it is not (at his time). How is the situation today? Can first-principle calculation accounts the ferromagnetism of iron quantitatively now?
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How can one reasonably theoretically model polycrystalline materials?

Many techniques are taught in advanced solid state courses but they are almost all derived for perfectly crystalline materials. For example, band structure really only appears theoretically when you ...