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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Relation between band structure, dispersion, density of states, and the Fermi energy and Fermi level

Despite the long title, this question is mostly qualitative (although I am interested in quantitative results if possible). Say you have an electronic band structure (energy as a function of "k") for ...
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121 views

Density Functional Theory (DFT) calculation for metals

Why is DFT not used in calculating electronic structures and properties of metals? I know DFT calculations are not accurate for metallic structures. Can someone explain why?
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23 views

Band structure and k vectors

If there is a restriction on the allowed states (k vectors) for a system, ie the no of states is equal to twice the number of unit cells in the crystal.. why do we plot k continuously on the x axis? ...
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55 views

Why dopant energy levels differ from one material to another?

Dopant levels in Si, Ge and GaAs are very different from each other. Even "similar" materials such as Si and Ge exhibit different dopant energy levels. (source: Pierret, Advanced Semiconductor ...
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52 views

What is theMost compressible material commonly found? [closed]

I'd like to know which solid material is highly compressable . I think plastic is widely available and quite compressable. What is something better?
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60 views

Elementary introduction to (quantum) hall effect

Where can I find an elementary introduction to classical and quantum hall effect? Only physics I know is some basic quantum mechanics, EM and statistical physics. My goal eventually is to understand ...
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24 views

conduction band and free electrons the properties of electrons in conduction band

Do electrons in conduction band consider as free electrons? or they are not completely free? so that we can calculate the distribution function and the density if states ??
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36 views

If I know how many atoms I have in a film, can I know the total magnetic moment?

Say I have a Co film and I know its volume so I know the total number of atoms in it. Using this plus the knowledge that each atom has a magnetic moment of 1.7 Bohr magnetons, would the total magnetic ...
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53 views

In what cases would using a non-resonant spectroscopy be preferable to using the resonant type?

Here it is mentioned that non-resonant Raman spectroscopy is desirable for avoiding fluorescence and for studying water due to water's low polarizability. How is non-resonant Raman desirable in the ...
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394 views

What is the significance of Fermi temperature?

The Fermi temperature of a solid is related to Fermi energy by relation $$ { E }_{ F } ={ k }_{ B }\times{ T }_{ F } $$ where $ { k }_{ B } $ is Boltzman constant. But what is the significance of ...
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31 views

Solving Bloch Waves for Potentials with Few Fourier Components

Suppose we have a potential in 1D $$U(x) = 2A\cos(\frac{2\pi}{a} x)$$ Let $G_\alpha$ be reciprocal lattice coordinates $$G_\alpha = \frac{2\pi \alpha}{a},\;\;\;\;\alpha\in \mathbb{Z}$$ As in Ashcroft ...
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44 views

Fermi Surfaces meeting

I know the fermi level is the highest energy level in an atom for its electrons and the fermi surface is (in reciprocal space) a sphere of radius fermi level, if that makes sense. So when two ...
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44 views

Why Solid Insulators have highest breakdown voltage?

Why does solid insulating materials have a higher breakdown voltage when compared to that of liquids and gases? Can anyone explain this in simple words?
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90 views

Particle Hole Transformation of Hamiltonian

The particle hole transformation for a bipartite lattice $\Lambda$ (with sublattices $A$ and $B$) can be written as $$U^\dagger c_{i,\uparrow} U = \epsilon(i) c^\dagger_{i\uparrow} \\ U^\dagger ...
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52 views

Sign conventions in Hubbard model

The Hubbard model is often expressed as $$H=-J\sum\limits_{<i,j>} \sum_\sigma c_{i,\sigma}^{\dagger}c_{j,\sigma} +h.c.+U\sum\limits_{i} c_{i,\uparrow}^{\dagger} c_{i,\downarrow}^{\dagger} ...
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60 views

What is the mechanism of heat exchange of a bouncing ball?

Imagine a falling ball on a perfectly hard ground. The kinetic energy will be first converted into a deformation of the ball, then the ball will restore it into kinetic and heat energy and recover ...
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24 views

Energy magnetization in the presence of temperature and chemical potential gradient

In the following paper (Phys. Rev. Lett. 97, 026603) http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.97.026603 the energy magnetization part of the energy current is given in the presence ...
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59 views

Valence bands question

I'm currently doing solid state physics and learning about semiconductors. During the course, I have seen a lot of energy/wavevector graphs, like this one (pic from Kittel): I did not have a ...
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46 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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840 views

Why are HCP materials brittle whie FCC materials are ductile?

Why are hexagonal close packed materials brittle, While face centered cubic is ductile. Is it related to crystal planes?
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19 views

Role of density of states of electrons in a solid

When studying the statistical mechanics of a solid such as a conductor or a semi-conductor, does the density of states of electrons play a role in the calculation of the heat capacities? I know that ...
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62 views

Mapping the first Brillouin zone to the nth Brillouin zone

The Brillouin zone can be constructed in the reciprocal lattice, by drawing bisectors to the lines that connect near neighbors. For example in the 2-D square lattice, the first Brillouin zone in red ...
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15 views

Why phenomena in different energy scale can be treated separately?

For example, there are electrons and lattice vibration in solid. The order of energy of electron is of eV which is much larger than that of lattice vibration. So they can be treated separately which ...
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127 views

Effects of massive magnetic field generated by operation of the large hadron collider?

I read an article about the CERN large hadron collider in which it talks about the magnetic field that is generated while the LHC is operating. A magnetic field more than 100,000 times more powerful ...
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Do metals *really* conduct at zero temperature?

The questions is mostly in the title, but might expose another of my misunderstanding of the band structure of solids and how that leads to metals and insulators. If we have a solid, and the fermi ...
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39 views

Landau levels in ferromagnets

Consider a spontaneously magnetised (uniformly) conducting ferromagnet. Now suppose that there is no external magnetic field. The question is as follows: will the motion of electrons be quantized via ...
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344 views

Why liquids and solids are mostly regarded as incompressible?

In many continuum-mechanical Problems it is assumed that liquid and solid substances cannot Change the total value of volume where it holds $\rho = const, \vec{\nabla}\cdot \vec{v} = 0$. In the ...
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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} ...
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127 views

If something is infinitely thin can it cut through anything? [closed]

Not sure if I heard this somewhere or how I came up with this idea but would something infinitely thin object be able to cut through everything effortlessly? For example, if I had a knife with its ...
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61 views

Heat capacity of solids

In the Einstein/Debye models, the specific heat capacity goes as T^3 at low temperatures and approaches the Dulong-Petit law at higher temperatures. I undestand that some molecular motions (rotation, ...
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71 views

different energies for the same k vector for free electrons in a solid

when we use the nearly free electron approximations for electrons in a solid and get them as plane waves the energy becomes $E=\frac{\hbar^2k^2}{2m}$, which gives us a parabola. but when we see the ...
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143 views

Density of States in NOT Free Electron Gas

I think that I understand how the density of states works for a free electron gas. It is effectively just a conversion factor between summing over values of k and integrating over values of E. If you ...
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88 views

Reduce integration over crystal to integration over unit cell

I am wondering when I can reduce integrals over a periodic crystal to a an integral over the unit cell. Especially I consider the following two-electron integral $$ I=\langle \varphi_i \varphi_j | V | ...
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Density of states and elliptic integral

It is known, for example Equation (14) in the graphene review of Castro Neto (arXiv), that the full expression for the density of states (DOS) of graphene is in terms of an elliptic integral. Close ...
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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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56 views

Is hysteresis essential for a memory system or material?

I want to know whether its essential for a memory system or material to have hysteresis between two of its variable ? If Yes, what can be the general relation of volatility of a memory with its ...
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121 views

Density Functional Theory (DFT) tutorial guide

I am going to start learning about DFT calculations. Could anyone advise me the best starting point for that? Simple example guiding tutorial with explanations would be great. Any input would be ...
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78 views

Tight binding on sawtooth 1D lattice

I am reading the paper "Bose condensation in flat bands" (arXiv). The authors consider a tight-binding model on the one-dimensional "sawtooth" lattice, comprised of two sites A and B in the unit cell ...
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113 views

Number Conserving Superconductors

Usual BCS theory used to describe superconductors violates particle number conservation, this is allowed since that theory is written in a grand canonical ensemble (i.e particles can be exchanges ...
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48 views

Why the Kondo effect is important for STM?

The Kondo effect is observed when approaching 0K. Why would this effect be important for STM?
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177 views

Non-uniqueness of the k-vector in Bloch state

How to understand that Bloch wave solutions can be completely characterized by their behaviour in a single Brillouin zone? Given Bloch wave: \begin{equation*} \psi_{\mathbf{k}}(\mathbf{r}) = ...
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295 views

Primitive unit cell of fcc

When I consider the primitive unit cell of a fcc lattice (red in the image below) the lattice points are only partially part of the primitive unit cell. All in all the primitive unit cell contains ...
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23 views

Why the centered rectangualr lattice is not considered a special case of an oblique lattice

From Wikipedia, there are 5 different kinds of lattice in 2 dimension: But I am wondering how the third type (the centered rectangular) is different from the first kind (the oblique lattice). The ...
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63 views

lattice vibration

I would like to inquire about acoustic and optical branch in Phonons vibration; My question is: what is the physics description when we say what is make acoustic and optical branch appear ...
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135 views

Do solids have translational energy?

Along with having vibrational energy, do both crystalline and amorphous solids also have translational energy? I ask because I've always understood solids to have just vibrational motion/energy. But ...
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14 views

What determines the Bloch wavepacket length scale?

We know in the semiclassical Boltzmann theory, there are several length scales: the lattice constant $a$, the Bloch wavepacket spread $\xi$, other length scales such as the mean free path $l$, the ...
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Tuning the frequency in graphene

As is well known, the frequency of transverse optical phonons in single layer graphene ranges from $10^{11}$ to $10^{12}$ Hertz. How can one "tune" the frequency to a specific value?
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Synthesis of Fe-based superconductors

Polycrystal cuprate superconductors are generally prepared by solid state reactions: Starting reagents are in powder form, they are mixed to each other and placed into furnace on high temperature ...
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70 views

Why does the stiffness of organic polymers (plastic) change so much with small changes in temperature?

This is on the borderline between Physics and Chemistry, but I would like a Physics perspective. I am guessing that plastics are a glass-like phase, rather than a true solid.
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Why is metal stiffer at lower temperatures?

Each morning I cycle to school and lock my bike with a thick steel wire (about 8 mm thick). I noticed that it's much harder to change the shape of the wire in the morning when it's much colder than ...