Questions tagged [solid-state-physics]

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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Is it possible for a thermoelectric generator to not have a heat source or heat sink?

Specifically, the type of thermoelectric generator I am suggesting makes use of the ExB drift effect. When electric and magnetic fields are perpendicular to one another, with infinite mobility of the ...
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Plausible finite group on-site-SPTs in realistic materials

I am looking for some understanding of which on-site symmetries in realistic crystalline materials (i.e. not just in random lattice models) can plausibly be expected to be realized and to induce ...
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How does amorphous $\rm SiO_2$ crystallize?

I know crystalline $\rm SiO_2$ changes its crystalline structure depending on temperature, but what happens to amorphous $\rm SiO_2$ if you heat it up? I could find nothing on this topic. Is it ...
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Why can a non-Metalloid be a Semiconductor?

I was reading that the first description of a semiconductor material was made by Michael Faraday in 1833 and published in Experimental Researches in Electricity.-Fourth Series (https://www....
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Why does doping allow for Cooper pairs in high temperature superconducting cuprate compounds in Resonating Valence Bond Theory?

Preface: I'm a first years masters student (only in my second quarter) and I'm well aware that RVB theory is an extremely complex and high level topic. I have to give a presentation for one of my ...
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What is $B(N)$ crystal structure? What does this nomenclature stand for

Is it basic cubic with 20 atoms? I can't find the explanation for this nomenclature online. Maybe I could find it in a textbook, but if someone answers it here, other people can just google it.
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Equilibrium carrier distribution appropriate to local temperature

In Chapter 13 of Ashcroft and Mermin there is a general discussion about the nonequilibrium distribution function under the relaxation time/semiclassical transport assumptions. One of the key axioms ...
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How to calculate the mass for phonon vacuum fluctuations?

I am studying this paper, the precise content of which isn't relevant for the question. In there, the authors consider quantized bulk vibrations in a diamond. As usual when quantizing such systems, ...
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Multi-electron Bloch bundles over powers of the Brillouin torus?

The quantum states of single electrons in a crystal famously form a (Hilbert) vector bundle over the Brillouin torus ${\mathbb{T}}^d$ -- the Bloch bundle. Does this theory usefully generalize to ...
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What is the mechanism of transparency of EM?

What happens in transparent materials? Do their molecules oscillate with the same frequency as the EM wave and then reemit in the same direction? Or the light goes through meshes in the bulk?
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Can the water remain in the vapor gas form at zero Kelvin (0K) temperature? (when the pressure is low enough or under other conditions)

Naively, when the water cools down to low temperature, the water goes to the ice solid phase. (Like below 0 celsius at 1 ATM pressure.) Can water remain in the gas form at zero Kelvin (0K) temperature,...
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What is the reduced mass of a diamond unit cell?

I am reading this paper to study so-called collapse models. However, the paper isn't really relevant to understand the problem here. In the paper, the authors are considering a bulk vibration (optical ...
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Landau tubes and Fermi sphere

a question regarding Landau tubes. I cannot understand why pictures of the Landau tubes are in k space as the Fermi sphere, especially considering the fact that $k_y$ ceases to be a good quantum ...
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Static dielectric constant and optical dielectric constant

I was reading Introduction to Solid State Physics of Charles Kittel (8th Edition), and the static dielectric constant is defined as $$\epsilon(0) = \epsilon(\omega=0) $$ and the optical dielectric ...
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Terminology: does this situation correspond to an anisotropic but linear dielectric?

Let us assume that for a dielectric the relation $${\vec D}=\epsilon\vec E$$ holds where $\epsilon$ is independent of $\vec E$. However, let $\epsilon$ is not a scalar number but a tensor (or a $3\...
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Can free electrons pass through the holes?

In crystalline silicon, when we say that free electrons can move until they fall into a hole, is it possible for that free electron to pass through the hole and continue to move?
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Diagonal long range order

I heard a lecture given by Professor Liu Haiwen. He said: off-diagonal long range order(ODLRD)$\rightarrow$BEC diagonal long range order(DLRD)$\rightarrow$solids ODLRD+DLRD$\rightarrow$supersolids ...
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Resonance level model: Commutator

As a small part of an exercise on the resonant level model (all fermionic (field-)operators, $\Psi(\vec{x}) = \sum\limits_{\vec{k}}e^{i\vec{k}\vec{x}}c_{\vec{k}} $, $V$ is a constant, $d$ and $c$ ...
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What is the mass of collective oscillations?

When you step through the procedure of deriving a phonon dispersion relationship for a given crystal structure (i.e. small oscillations from equilibrium, harmonic approximation, collective coordinate ...
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Matrix components of energy of simple cubic crystals

Im working through the derivation of the paper by Slater and Koster (1954) http://users.wfu.edu/natalie/s15phy752/lecturenote/SlaterKoster.PhysRev.94.1498.pdf Im having trouble working through table 2....
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Symmetry breaking in near free electron?

In 1D lattice, if we consider a near-free electron model, ie. $$\hat{H}=-\hat{\psi}^{\dagger}(x)\frac{\nabla^2}{2}\hat{\psi}(x)+V(x)\hat{\psi}^{\dagger}(x)\hat{\psi}(x)$$ where $V(x)$ is a periodical ...
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Questions regarding physical electronics [closed]

I ran into some questions while studying physical electronics. My textbook/lecture note says "An electric field applied to a semiconductor will produce a force on electrons and holes so that ...
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1 answer
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What is the relation between phonon anharmonicity and thermal conductivity?

The textbook says that: if the vibration of the lattice were harmonic, then the states of phonons would be orthogonal to each other. As a result, there would be no interaction between phonons, hence ...
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1 answer
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What is the meaning of this wave function?

In these notes here the tight binding model for graphene is worked out. The tight Binding Hamiltonian is the usual: $$H=-t\sum_{\langle i,j\rangle}(a_{i}^{\dagger}b_{j}+h.c.)$$ where two different ...
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Bragg-Williams microcanonical esemble

In this question Bragg-Williams theory of phase transition of the forum someone was asking for Bragg-Williams aprox. and how to calculate entropy. The answer is clear and correct, the Bragg-Williams ...
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2 answers
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Valley degree of freedom in graphene

I know that in the energy band structure of graphene there are six points where the valence and conductance band touch (At $E=0$), called Dirac points. Only 2 of these points are inequivalent, K and K'...
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What does a negative wetting tension $\delta F$ mean?

If a solid polymer has a drop of liquid (water) and shows a negative value of wetting tension, what does this mean? Does this mean that the drop of liquid will bead up instead of spreading on the ...
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Density states of phonons with different speed at different directions:

I was trying to get the density of states $g(v)$ for phonons which have $2$ polarizations transversally, and $1$ polarization longitudinally. My approach: $$dN = \frac{1}{8} 4 \pi n^2 dn, \lambda = c/...
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Identical atoms in a potential energy well given heat

When two neutral atoms in the potential energy well are given some amount of heat, why does the distance between them tend to increase? It seems to me from the potential energy versus distance graph ...
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4 votes
1 answer
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On $k$-space density of states and semiclassical transport

I am reading Chapter 12 of Ashcroft and Mermin and I have a great many questions, but one sticks out in particular. As background, we note that it can be shown quite generally (by applying Born-von ...
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Para- and ortho-excitons in solids with spin-orbit coupling

The names para- and ortho-exciton stem from the fact that -- in superficial analogy to para- and ortho-hydrogen -- the wave function that forms the electron-hole bound state can either be a singlet ...
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Why Hamiltonian for a Solid is periodic in Bloch Theorem?

It is as simple as the title and more general to Bloch theorem treatment. In any periodic infinite solid lattice, we say that the potential will be periodic. This makes sense, but how do we know that ...
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Quantum well in confining structure

I was studying the confining of electrons in a composite crystal. I don't understand how the fact that the band gaps of the two materials are different translates immediately to the statement that ...
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Spectrum Symmetry Matching Condition in Quantum State Transfer

I am currently working through some background theory on a project attempting to show perfect quantum state transfer using a 1D Hubbard Model. The researchers whose work this project is elaborating on ...
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1 answer
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Allowed energy levels in an $E$-$k$ diagram

For a particle confined in an infinite potential well in 1D, the $k$ value is quantized as $k=nπ/a$, where $a$ is the length of the region where $V(x)=0$. However, the $E$-$k$ diagram derived from ...
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8 votes
2 answers
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Berry curvature concentration around nodal points

It is well-known that in TI-symmetric semi-metals the Berry curvature on the Brillouin torus vanishes away from the nodal points (eg. [XCN10, III.B] [Van18, p. 105]). But even for non-TI-symmetric ...
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1 vote
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Mott-Bethe electron scattering factor at g=0

I am a non-physicist, but am doing some calculations related to electron diffraction in (crystalline) solids. Generally, electron scattering factors $f_\text{e}(s)$ can be estimated from the xray ...
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3 votes
3 answers
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How is this expression for the energy of a free electron gas derived with the canonical ensemble (Ashcroft and Mermin)?

Suppose we have some system of free electrons in a (say, 3D) box at a temperature $T$. From Ashcroft and Mermin equation (2.55), we can compute the energy of the system as $$U=2\sum E(\mathbf{k})f(E(\...
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Evaluating electric conductivity using Kubo formula. Scalar potential vs vector potential

It is well known that the electric field can be written in terms of scalar $\phi(r)$ and vector $A(r)$ potential as $E=-\nabla\phi - \partial_tA$. Then the Hamiltonian $H_{ext}$ for the ...
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Fermi energy lying in the forbidden gap

So, according to the my textbook(Fundamentals of physics by Halliday & Resnick), the Fermi level is the highest occupied level at absolute temperature ($T=0 K$) and the energy corresponding to it ...
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How is ballistic transport detected/measured experimentally?

That is, measuring the current and calculating the resistance for conducting materials of extremely small size and short paths(such as nanowires for example). How is this done in a laboratory?
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(Anderson Localization)Time evolution of occupation number of free fermion model

I encounter a difficulty in comouting the time evolution of occupation number. I want to compute the time evolution of occupation number of Aubry-Andre model to show that there exists Anderson ...
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3 votes
4 answers
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Doubt about interpreting Fermi level in semiconductors

Before I say anything, I know there's already a bunch of questions about the Fermi level in semiconductors on this website but I don't think my doubt in particular has been addressed before. From what ...
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1 vote
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Energy transfer and electromagntism

How is kinetic energy from one moving macroscopic object to a stationary object is transferred at a particle level? Is all energy transfer that exists an effect of electromagntism at the particle ...
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3 votes
1 answer
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Calculating bulk modulus from interatomic potential on cubic lattice

How do I account for the lattice structure of a solid when computing the bulk modulus, given an interatomic potential? The bulk modulus, $B$, can be expressed as the second derivative of the ...
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Evaluating a commutation relation - (Mahan's book)

I am trying to replicate one of the equations from Mahan's Many-body theory book. First the Hamiltonian $H$ is defined as: $$ H = \sum_i h_i \quad;\quad \text{where} \quad h_i=\frac{t}{2}\sum_{a}[c_{...
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1 vote
1 answer
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Relation between Fermi surface and Fermi velocity

Is there a direct relation between the Fermi velocity and the Fermi surface? Can one reconstruct the Fermi surface if the full angular distribution of the Fermi velocity is known?
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Electronic bands and Aufbau principle

In atomic theory there is Aufbau principle stating (Wikipedia) The rule states that for a given electron configuration, the lowest energy term is the one with the greatest value of spin multiplicity. ...
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2 votes
1 answer
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How do I calculate/approximate chern number from band structure?

I know this is a similar post to Calculate Chern number from band structure but it has not been answered for 3 years so I want to make a repost, sorry. I did not make the original post so please don't ...
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Rabi oscillation in a solid

I have 2 questions regarding Rabi oscillation: Can we observe Rabi oscillation in a solid? Most of the articles that measured Rabi oscillations were made either on single atom, quantum dot, but ...
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