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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Can we say an atom is ferromagnetic?

Some atoms have nonzero magnetic moments. Does it make sense to say they are ferromagnetic? Or should we say it is paramagnetic?
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Time reversal operator in tight-binding model with second quantization form

In the tight binding model, $H=\sum_{r,r'}ta^{\dagger}_{r}a_{r'}+h.c.$. When conducting a time reversal transformation, what form will this Hamiltonian take? Or how can I express time reversal ...
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94 views

Lattice geometry and dispersion relation

Is there a general theorem which gives some information about which influence have the lattice geometry (for example sub-lattice structure, square lattice, honeycomb lattice, lattice symmetries, ...) ...
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In which direction along a GaN (wurtzite) crystal are only Ga atoms being observed?

So, if you have an electron microscope image of a GaN crystal, and that it shows only white dots which represent Ga atoms. No nitrogen atoms are seen in the image. Along which direction is this ...
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What is a re-entrant energy contour in a band structure?

I have a question involving band structure in solids. What does it mean to say that an energy contour in a band structure is re-entrant? Herbert Kromer uses this term in: H. Kromer, Phys. Rev. 109, ...
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340 views

Intro to Solid State Physics

I didn't see this listed on the books page so here it is. I'm currently in an introductory Solid State course, and we are using Kittel's book. I have been having a rough time with this book although I ...
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107 views

Coordinate system for crystallographic groups

In the International Tables for Crystallography for each crystallographic group an asymmetric unit is supplied (mathematicians call this a fundamental domain of the group). This region is a bounded ...
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218 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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Most True to Life Physics & Biology Simulation Engine? [on hold]

I'm a programmer. I code in C++, C#, HTML5, and PHP. There are many graphics engines I have at my disposal. The question is: Does there exist a graphics engine that is as true to our reality as ...
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the derivation of the “spectral function”

My question is from this article at page 8, from eq21 to eq 25. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.34.5179&rep=rep1&type=pdf That is, I got stuck while deriving ...
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164 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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43 views

Is this crystal defect an example of dislocation or a vacancy

It looks to me that a regular hexagonal pattern formed by the Ga atoms is interrupted in the middle of the crystal. Is this a void (or vacancy...), dislocation or another type of defect? Plus what ...
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106 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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154 views

How does a band gap arise from the 3D Kronig Penney model?

The Kronig-Penney (KP) model is a classic model that is used to show that a periodic lattice of finite well potential sites will give rise to a band gap. The typical process in solving the KP seems to ...
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116 views

Flaw in Einstein's explanation of the photoelectric effect?

The essence of Einstein's idea is like this: if a system is in some bound state with energy $-E_b$ with $E_b> 0$ (the threshold of the continuum band is taken as zero), and we drive the system ...
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How can I calculate the character table for double group in spin-orbit interaction

When I read the book(Group theory: application to condensed matter physics) page 347, I found I don't know how to derive the new irreducible representations in the double group.
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120 views

What does $m^*>m_e$ imply? (the effective mass of electron is larger than its rest mass)

From what I understand, the concept of effective mass is just something people come up with to make electrons and holes obey the equation of motion $$ \vec{F}=m^* \vec{a} $$ without dealing with the ...
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151 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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Hamiltonians on tensor product states

Solid state & Atomic Physics. The wavefunction for the electrons is $\psi(\mathbf{r}, \mathbf{R})$, where $\mathbf{r}$ is the position of the electron and $\mathbf{R}$ of the nucleus. The ...
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107 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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What is the spin of a magnetic impurity?

I am reading this seemingly important paper Local Magnetic Moment Associated with an Iron Atom Dissolved in Various Transition Metal Alloys. It is strange to me that the magnetic impurity has ...
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1answer
485 views

Pauli paramagnetism for electrons with external magnetic field

Apparently it is to be shown that for electrons under an external magnetic field, in the limit as $B\to 0 $ $$ \chi = \frac{dM}{dB} \approx \frac{n\,\mu^{*^2}}{k\,T}\,\frac{f_{1/2}(z)}{f_{3/2}(z)} $$ ...
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310 views

If my lattice has an atomic basis, do I also find the reciprocals of the basis vectors to get the reciprocal crystal structure?

That is what my crystal structure looks like. The blue atoms sit on every lattice point (basis vector of $\{0,0\}$) and the red atoms have basis vector of $\left\{{2\over3},{1\over3}\right\}$. The ...
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What kinds of behavioural anomalies can a zero-field-cooled (ZFC) / field-cooled (FC) split indicate?

If a material shows a spiltting in the ZFC and FC curves, is it necessarily superparamagnetic, or could there be any other reason for the irreversibility? I have heard spin glasses also show ZFC-FC ...
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176 views

In a positively biased 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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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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Normal modes and lattice symmetry

In chapter 22 of Ashcroft & Mermin, it says: Theorem: any transformation that leaves $\mathbf{k}$ and the lattice invariant must transform one normal mode with wave-vector $\mathbf{k}$ to ...
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“Bosons are either gapped or condensated, except physical principle protected cases (Goldstone boson, photon).”?

Bosons are either gapped or condensated, except physical principle protected cases (Goldstone boson, photon, etc.). I read this in a paper (version1 of http://arxiv.org/abs/1404.3728v1, 1st page 1st ...
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126 views

Volume of Brillouin zone is the same as Fourier primitive cell?

In Kittel's solid state text, problem 2.3, he says that the volume of the Brillouin zone is the same as a primitive parallelepiped in Fourier space. Somehow I can't see why this is true. Can someone ...
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122 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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120 views

Why is the law of the p-n junction valid under forward bias?

I'm currently studying the physics of the PN junction. I went though the derivation of the built-in potential in the PN junction under equilibrium: $$ {Diffusion\ current\ density} = {Drift\ current\ ...
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28 views

Resonant vs. Non-resonant Raman

What does it mean to say that the conventional Raman effect is non-resonant? And, how/why does resonant Raman give a stronger signal than the non-resonant type?
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Origin of band Gap

I know that in the Kronig Penney model there are values of the energy $E$ for which solutions to the Schrodinger equation don't exist. I understand that these forbidden values of $E$ form the band ...
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157 views

Diffusion and Drift currents in a PN junction

In a forward-biased PN junction, the potential barrier decreases, allowing more majority carriers from one side to diffuse to the other side where they are minority carriers. After they cross the ...
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36 views

Hamiltonian for semiconductor

I was wondering which terms we need in a semiconductor Hamiltonian where no transition between the valence and conduction band occur? First we would have a term describing the energy of the full ...
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64 views

Interpretation of Fermi-Dirac statistics

I was reading that as temperature increases the energy at which $n(E)=0.5$ shifts to lower energies as these lower energy states become depopulated. Could someone explain that, what it means and why ...
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865 views

Relation between density and refractive index of medium

Is there any relation between Refractive index and density of a material? It is not found to be proportional in my experimental results. Is there any equation to relate these parameters?
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Capacitor of Pearson–Anson oscillator

I was calculating capacitance of Pearson–Anson oscillator and comparing with simple RC circuit but I get two different values. They have significant difference. I am not clear why do they have. Could ...
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28 views

Integrals in tight-binding method

In the tight-binding method, as e.g. described in Ashcroft and Mermin one need to solve a few integrals in order to proceed. For example for the overlap between an orbital situated at two different ...
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54 views

Work function definition

As in this post How would I calculate the work function of a metal, the definition is given by "the minimum thermodynamic work (i.e. energy) needed to remove an electron from a solid to a point in the ...
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Why is calcium paramagnetic?

As far as I understand, magnetism comes from the 'unpaired electrons' in the subshells of atoms. Atoms with paired electrons are diamagnetic ('not magnetic') while atoms with unpaired electrons are ...
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60 views

Energy conservation of permanent magnets engine

How to explain the fact that magnet can attract an object (apply a work W) without losing a (significant) part of its internal energy? How to apply the energy conservation principle? Please think to ...
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67 views

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 ...
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60 views

How holes conduct current?

I had questions about holes in semiconductor, when i checked the net it is said holes are said to be equivalent positive charge and they say because the hole moves from one place to another when it is ...
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Tight binding in the limit of large system size

Suppose that one has a continuous Hamiltonian with spin-orbit interaction, for example $H=-\dfrac{\mathbf{p}^2}{2m} +\kappa({\boldsymbol\sigma}\times\mathbf{p}) + U(x)$ and want to approximate this ...
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How to derive De Haas–van Alphen effect?

I was reading Solid State Physics by Kittel and they manage to derive De Haas–van Alphen effect by invoking the Bohr-Sommerfeld model. This feels unsatisfactory to me. Can someone derive this using ...
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30 views

Is it possible to get the (Pauli) repulsive term in the Lennard-Jones potential from theoretical considerations?

Title says it: Is it possible to get the form of the (Pauli) repulsive term in the Lennard-Jones potential from theoretical considerations, or is it purely found experimentally through fits?
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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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What exactly is cutting with a knife will look like on the atomic scale? [duplicate]

Some times I like to view the world in the microscopic scale .ie. at this level all objects any thing will be collection of atoms which we normally don't view with our naked eye. At that scale I ...