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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Uncertainty principle characterizing metallic bonding?

So I was trying to think through the statement that the uncertainty principle can characterize metallic bonding. I know that the uncertainty principle is: $\Delta p \Delta x = \frac{\hbar}{2}$. And ...
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Does the Fermi sea have plane waves, or wave packets?

Consider a zero-temperature, one-dimensional crystal with allowed electron momenta $k_n = \frac{2\pi n}{L}$. Question: Which is the more correct way to think about the Fermi sea? Sharp plane ...
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Fermi Energy and the Electric Potential

In an extrinsic semiconductor the electric potential is: $$\phi = \frac{1}{q}(E_{\mathrm{F}} - E_{\mathrm{Fi}})$$ where $E_{\mathrm{F}}$ is the Fermi energy, $E_{\mathrm{Fi}}$ is the intrinsic Fermi ...
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173 views

The origin of contact noise?

I was trying to measure the noise of a device with metal probes. I was not sure whether I should trust the results because I was told contact noise might contribute to some degree. I am a little ...
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103 views

Thermal expansion and conductivity

When thinking about how the lattice constant of silicon can be given up to eight decimal places without a remark for the temperature I realized that, it seems most insulators and semiconductors seem ...
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151 views

Typical time scales for spin dynamics and lattice vibrations in magnetic solids

In a paper from the 1990s ([1]) on magnetovolume effects in ferromagnets, it is written that in most real situations, the moment (or spin) autocorrelation time is much larger than the period for ...
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168 views

Brillouin Zones in a nanowire

My professor told me something I didn't understand the other day: I was reading a paper on a crystalline nanowire (NW), and in the paper they look at how the band structure changes (from that of the ...
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115 views

The boundary between polycrystalline and crystalline

My current understanding of solid crystalline-like materials (please correct me if I'm wrong!) is that it is a continuum in terms of crystallinity, from amorphous (basically no periodicity) to single ...
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94 views

Phase diagram of SO(5) rotor model

It was originally a problem from Professor Eugene Demler's problem set. Consider an SO(5) rotor model: \begin{align}\mathcal{H}=\frac{1}{\chi} \sum_{i,ab}L_{ab}^2(i)-J\sum_{<ij>,a}n_a(i)n_a(j)+...
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147 views

Why does silicon have an indirect gap?

Is there an intuitive explanation as to why silicon has an indirect gap? I have heard that this can explained using pseudopotentials.
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173 views

Stiffness tensor

Let's have a stiffness tensor: $$ a^{ijkl}: a^{ijkl} = a^{jikl} = a^{klij} = a^{ijlk}. $$ It has a 21 independent components for an anisotropic body. How does body symmetry (cubic, hexagonal etc.)...
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Discrete sum over an exponential with imaginary argument, considering only every second lattice site?

Let's say I sum an exponential function $e^{\imath \left(k-k^{\prime}\right) x_{i}}$ over a chain system where every member of the chain is of the same type, e.g., A-A-A-...-A-A (total of N sites) ...
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167 views

What does plasmon look like in 3D band structure graph?

Consider metal, and its reciprocal lattice representation with Fermi surface. What is the correct way to represent a plasmon in this system? M.b. rotating points on the surface? Or 3d membrane-like ...
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Why does AC Conductivty in Drude Theory have an Imaginary and a Real Part?

In the Drude Model the direct current (DC) conductivity is given by the following formula: $$\sigma_0=\frac{ne^2 \tau}{m}$$ where $\tau$ is the relaxation time. Furthermore, the AC conductivity in ...
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20 views

Deriving Reciprocal Lattice Definition

The derivation of reciprocal lattice vectors in terms of the direct space lattice vectors starts by applying expanding a translationally invariant lattice function $f(\bf{R_k}+r)$ in plane waves $f_k ...
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41 views

Density of States for a separable hamiltonian

There are $N$ non interacting electrons in a potential well: \begin{align} H&= -{1 \over 2 } \nabla^2 + U(x,y,z) \\ U(x,y,z)&={1\over2}\omega^2z^2 \; \mbox{for} \; (x,y) \in [0,L]\times [0,L]; ...
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Why can we extract the oxidation state from XPS and XANES but not from XRF or EDX?

To my understanding it is possible to extract information about the valence/oxidation state of an ion in a material by using X-ray photoelectron spectroscopy (XPS) or X-ray absorption near edge ...
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38 views

Simplifying three mass, two springs system

I have a system of three equal masses connected by two equal string system. x_1 x_2 x_3 *--------*---------* ------> x M k M k M ...
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Solutions for Kittel's Introduction to solid state physics 6th edition?

I'm looking for the solutions of Kittel's 'Introduction to solid state physics' 6th edition. I can only seem to find the solutions for the 8th edition online. Does anyone have the pdf to it? Or ...
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35 views

Is disturbance propagation velocity equal to wave velocity in a solid body?

How do the disturbance propagation velocity and wave propagation velocity relate to each other? To explain my question in details I will describe the following situation from the theory of acoustic ...
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26 views

Lattice sums (solid state physics)

The potential in a crystal doesn't only depend on the distance between 2 atoms, but also with the interaction to all $j^{th}$ neighbour-atoms. The Lennard-Jones-Potential then becomes $U(R_j)=\...
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19 views

Database for work functions for exotic crystallographic faces

Is there a database, which holds work functions (found either from experiment or calculations) for some more exotic crystallographic faces, such as (221) or (311) for copper? I dug around and found ...
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It it true that the Fourier transform of the return probability can be written as the product of the retarded propagator & the advanced propagator?

I know the retarded green's function $G(r,r; E)$ is expressed as $$G(r,r; E)=\sum_n \frac{|\mu_n(r)|^2}{E-E_n+i\eta}$$ with the eigenvectors/eigenvalues $\mu_n(r)/E_n$. This expression of $G(r,r; E)$ ...
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Fermi surface reconstruction and fermi pockets

Certain quantum phase transitions are characterized by the emergence of some ordering wavevector $K$ : antiferromagnetism, charge or spin density waves, among others. In the case of Néel ...
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Why the bandgap of inorganic semiconductors decreases with temperature?

The temperature dependence of the energy bandgap in inorganic semiconductors is given by $$E_g (T) = E_{g,0} - \frac{\alpha T^2}{T+\beta}$$ where $\alpha, \beta$ are both positive, and the (somewhat ...
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what is the effect of temperature on the resistance of a photoconductor?

As we know, for a photo conductor resistance tends to decrease with increase in irradiance, but with greater irradiance comes greater temperature. Also we know, photo conductors are semiconductors,...
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Space groups and crystals. Simple example for the diamond structure

I try to learn the basis notions in crystallography and space group. But I already fail at the beginning. Let me give you an example: Consider the diamond structure (space group $Fd\overline 3 m$, ...
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Surface potential and symmetry breaking

I am studying surface states currently and am a little confused about something. If I consider p-orbits on a surface state that is the top layer of an HCP structure -- I understand the hopping terms ...
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What's the difference between an exciton and a geminate pair?

In the context of organic solar cells, electron-hole dissociation is sometimes mentioned with regard to excitons (refs 1, 2) and sometime with regard to geminate pairs (refs 3, 4). Also, exciton ...
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Why singlet and triplet states are not mentioned when dealing with inorganic semiconductors or other heavy materials?

Singlet and triplet states get attention in organic materials (fluorescence, phosphorescence, upconversion). Why singlet/triplet states are never mentioned in the context of inorganic semiconductors, ...
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24 views

Why isn't every magnetic neutron scattering peak a nuclear scattering peak as well?

Neutron diffraction is a well-established technique for determining the magnetic unit cell of magnetic materials. The idea is that nuclear scattering gives you peaks that correspond to the crystal ...
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Hopping integral for Hydrogen chain

When calculating a hydrogen chain in the tight binding approx., one comes across the hopping integral: $<m+1|V_{m+1}|m>$ Where $|m>$ is the 1s-Wavefunction at position m and $V_m$ is the ...
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How to write Fractional Quantum Hall States with Symmetric Polynomials?

Is there a link between Fractional Quantum Hall States and Symmetric Polynomials. In papers of Xiao Gang Wen [1], [2] work out a few examples: $ \Phi_{1/2} = \prod_{i < j} (z_i - z_j)^2$ is the ...
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In non-metallic solids w/ just atoms or ions (no molecules), are bonds (vibrations) and electronic transitions the sole cause of blackbody radiation?

Since there wouldn't be a conduction band filled with any electrons in a non-metallic solid made of just atoms or ions (no molecules), it's hard to imagine any other type of movement and dipole moment ...
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The probability of photoluminescence

Was reading about premeditated doping in semiconductors and the effect it imposes on the emission spectrum, doping as I read introduces defect states which are close to either the valence band edge or ...
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Intersection of $\rho_{xx}$ and $\rho_{xy}$ in Drude magnetotransport

Okay, so I've recently been working through the rather elementary derivation of the Hall effect in a 2 dimensional electron gas, using the Drude model. The idea is that with an E field in the x ...
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Will using the WKB method for tunneling current give incorrect results for specifically low applied voltages?

I am simulating quantum tunneling through a rectangular potential barrier, as a function of applied voltage across the barrier as well as barrier thickness. I am following the theory from the book "...
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55 views

Many-particle operators in the occupation number representation

I've read that if we have a many-particle operator in the coordinate representation which is the sum of identical one-particle operators operating, however, on different particles, like $\hat{Q} = \...
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23 views

How do phonon modes and other collective atom processes fit in with the Clausius-Mossotti relation?

The Clausius-Mossotti Relation relates the molecular polarizability of a chemical (that is, how much an electric field polarizes the molecule) to its dielectric constant, which determines its optical ...
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53 views

Photon absorption and emission in 2nd quantization

I am looking for models which describe the interaction of matter (lets take a 1D chain of atoms) with photons, especially the emission and absorption. I would love to see the derivation of models in ...
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24 views

Properties of materials _not_ dependent on fermi surface?

So I'm studying a second solid state physics course where we've covered calculating things like magnetic susceptibility, specific heat and resistivity by considering excitations of electrons around ...
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48 views

Band-gap for solids with isoelectronic atoms

Isoelecronic atoms have same number of electrons but different nuclear charge. It is said that many of the chemical properties of these elements are equal or at least similar. Can I form solids with ...
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Coulomb potential of a periodic crystal in reciprocal space

Usually the Coulomb potential (electron-electron interaction) can be Fourier transformed (aside from prefactors) like that: $$ \frac{1}{|\vec r_1 -\vec r_2|} = \int \frac{\text d ^3 k}{(2\pi)^3} \frac{...
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Why aren't most ionic/covalent/metallic materials self-healing?

For the most part, only soft-matter materials appear to possess self-healing capabilities (that is, if I cleave the material and then press the two halves together, the material re-forms) at room ...
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78 views

Connection between Lindhard susceptibility and Free energy

I've encoutered a few times, but I never got an explanation for it... How is the spin-dependent Lindhard function for the dynamical susceptibility of an electron gas $$ \chi_{\sigma,\sigma'} (q, \...
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Do the fourier components of a periodic function need to satisfy the boundary conditions imposed on it?

I cannot understand the opening statement of the second derivation of Bloch's theorem in the solid state physics book by Ashcroft and Mermin (Chapter 8, eqn 8.30). We start with the observation ...
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Underdoped Cuprates

What does underdoped cuprates mean? I guess cuprate is underdoped when hole concentration is less then optimal doping. Am I Right?. or it is something difference?
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How to do continuum approximation?

Assume you have $N$ matrix fields $T_{j}$ on a 1d lattice with lattice constant unity. Now consider a sum like the following (you can think of the traces as supertraces), and subject it to a continuum ...
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What does “fully depleted” mean?

In many papers/articles on CCDs, particularly those used for dark energy surveys and dark matter detection, the term "fully depleted CCD" is used. What does this mean? References: http://arxiv.org/...
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e-e scattering time in graphene

I think its worth writing my second question in this post as a separate one. In normal Fermi liquid, the electron-electron scattering time $\tau_{e-e}$ is about: $$ \tau_{e-e} \approx \frac{\hbar ...