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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Energy-band diagrams of heterojunctions

I'm studying heterojunctions and I'm struggling with drawing their energy-band diagrams. I've been looking for books or something to look up how the diagrams can turn out to be with different types of ...
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What are pure solids? Can we call every pure solid as a crystal?

How many types of pure solids do we have? are we still finding new pure solids or Are these pure solids limit in number?
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what is the sharp step, terrace in stm image?

hi i`m interested in stm so i have read some paper about stm. but lack of my background, i have trouble with understanding. paper says that sharp steps, flat terraces and few serface imperfection ...
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Why does a higher gate voltage increase electron density + mobility in a 2DEG?

I have a question concerning a 2DEG created in a n-AlGaAs / GaAs heterostructure: If the n-doped AlGaAs is on the left side and the GaAs on the right side, the following band structure will appear: ...
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How exactly to build the band diagram for photonic crystal?

How to build a band structure for the photonic crystal? I'd like to understand the full train of thought. I understand that we go on the perimeter of irreducible first Brillouin zone and somehow copy ...
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56 views

Using the momentum-space definition of the position operator in position space?

For the position operator $\hat X$: $\hat X \rightarrow x$ in position space $\hat X \rightarrow i \frac{\partial}{\partial k_x}$ in momentum space Question: Can $\hat X \rightarrow i \frac{\...
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35 views

Distance between adjacent planes in a crystal

This question has been asked before, but there doesn't seem to be a decent answer. Many sources state that " For cubic crystals with lattice constant a, the spacing d between adjacent (ℓmn) lattice ...
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How to calculate the eigenstate of a lattice model in the position space

Say we have a triangular lattice, inside the unit cell there are four sites(label them as a, b, c, d) with different on-site potential energy. What I want to do is find the eigenstate in the position ...
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Why are magnetic quantum numbers assigned like they are assigned in the paper on WS2 monolayers?

Now I'm reading the following paper: Sie, E.J., et al., 2015. Valley-Selective Optical Stark Effect in Monolayer WS2. ‎Nat. Mater., 14, 290-294 And they assigned magnetic quantum number to valence ...
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What happens to a radar signal when it meets with a superconductor? [duplicate]

A radar system has a transmitter that emits radio waves called a radar signal, consisting of electromagnetic radiation. What happens when it meets with a strong superconductor, considering the fact ...
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The two point fluctuation autocorrelation function in computing the scattering intensity?

In this paper: http://www.pnas.org/content/113/8/2029.full.pdf?with-ds=yes and: http://www.pnas.org/content/113/8/2029.full.pdf The authors try to compute the scattering intensity for a simulation ...
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Stoner-Wohlfarth model for ferromagnetism

I'm studing the Stoner-Wohlfarth model for ferromagnatism on the book Ibach-Luth Solid state physics. During the derivation of the Stoner criterion I found this passage (8.43) not so clear for me: ...
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Projected band structure plot - orbital characteristics plotted vs the K values?

I'm not understanding what is it that I have to plot for obtaining the orbital characteristics of a band in the band structure diagram. Usually we plot the energy eigenvalues for a given k point. ...
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3answers
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Mean energy of free electrons

My textbook states that the mean energy of free electrons within a solid state is given by $$ E_{av} = \frac{U}{N} = \frac{\int_0^{k_f}D(k)E(k)dk}{\int_0^{k_f}D(k)dk} $$ where $D(k)$ is the density of ...
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Hamiltonian formulation of the semiclassical Model of electrons

I'm currently reading the book Solid State Physics by Neil W. Ashcroft and N. David Mermin. In Chapter 12 they introduce the "Semiclassical Model of Electron Dynamics". In short: After having solved ...
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2answers
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Why the cooper pair do not obey the exclusion principle?

In superconductivity, which occurs in certain materials at very low temperature, electrons are linked together in cooper pair. And why the cooper pair do not? Thank you in advance.
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Classical Mechanics as an approximation of Quantum mechanics [closed]

I want to show an equality: We know from Ehrenfest's theorem that $$ \frac{d \langle x \rangle(t)}{dt}= \left\langle \frac{\partial H}{\partial p} \right\rangle $$ I'd like to derive the ...
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Connection between Bragg diffraction off BZ planes and opening of a band gap

I have a hazy idea that comes from a few video lectures where the following is stated: The condition for constructive interference (Bragg condition) in reciprocal space is that the wave vector should ...
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Eigen energy of the Landau levels in a tilted magnetic field

The problem pertains to a fermi gas in a tilted magnetic field confined by a harmonic potential in the z direction. I chose the vector potential $(0,ax-bz,0)$. I obtain the following hamiltonain with ...
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Any good books on the physics of semiconductor devices?

I know there are many books on semiconductor devices. But, it seems that many of them are catering to the engineers, not physicists. Namely, the books lack the theoretical depth. So, is there any ...
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2answers
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What is the difference between crystals and solid? [closed]

In condensed matter physics, what are the differences between crystals.
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1answer
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Can Non-Magnetic Dust Particles become magnetic if their particle size is decreased (by grinding them probably)?

Problem: Take some dust particles whose size is big. Bring a magnet near them. They do not get attracted to the magnet and thus we conclude that they are non-magnetic. However, when you grind the ...
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Why Weyl fermion in Weyl semimetals(WSM) have high mobility only at low temperature?

I read several papers reporting high Weyl fermion with very high mobility in WSMs such as TaAs, NbAs, WTe2 and so on. However, this high mobility looks like (=Weyl fermion) always appears at only low ...
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3answers
55 views

Could dark matter possibly be anti-matter?

Considering the broken symmetry after the big bang - what I understand as there being a huge surplus of matter and a lesser presence of anti matter - is it possible that dark matter could be anti-...
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Resistance increase with length because of more scattering?

I am referring to one of the answers to this old question. I can't add comment to it because I don't have enough reputation. So here I rephrase the question: does resistance increase with length ...
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How do i calculate leakage current in passivation layer of GaN HEMT?

I want to calculate the leakage current between the passivation and encapsulation layers of the GaN HEMT which will give me information about the material
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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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Third Brillouin zone for a quadratic 2D lattice

As far as I understand, the construction of Brillouin zones stems from the relation $$ 2 \vec{k}\cdot \vec{G} +G^2 = 0$$, where k is the wave vector and and G is the reciprocal lattice vector. This ...
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1answer
34 views

Out-of-plane electronic band structure for 2D materials?

There's been much recent interest in 2D materials since they can form monolayer-thick films. Since their crystal structure is periodic along the in-plane directions, the electronic band structure ...
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1answer
55 views

Solid state physics: When do I use classical laws?

Let's say I am given the dispersion relation for nearly-free electrons: $$ E(k) = \frac{\hbar^2}{2m}(k^2+c\,k^4)$$ Where $c$ is a small constant of appropiate dimension. How do I calculate the ...
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2answers
73 views

How do signals go through solid objects? [closed]

So many types of signals pass, or seem to pass I don't know, through solid objects. How do they do this?
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55 views

Intuition for defining basis for Hamiltonian in momentum representation

I am going through Quantum information approach to the Ising model: Entanglement in chains of qubits by Stelmachovic et al. In Section A.4, the authors determines the eigenvalues and eigenstates of ...
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45 views

Speed of sound in solid — temperature dependence

Let $v$ denote the speed of sound in a fixed solid, at a fixed temperature $T$. This will depend on properties of the solid (such as the bulk modulus and density). Given an increase in $T$, does $v$ ...
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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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Bosonization for unequal left/right Fermi velocities

The standard exposition of bosonization/Luttinger liquid theory in textbooks treats the case that left and right channels share the same absolute value of Fermi velocity. Is it possible to relax this ...
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How to confirm experimentally the effect of momentum space Berry curvature in solids?

I'm studying spin-orbit coupling and Berry curvature effects, especially on the spin Hall effect. However, Table 3 in a review paper http://journals.aps.org/rmp/abstract/10.1103/RevModPhys.87.1213 ...
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How can I derive the Phonon Density of Normal Modes in two and three dimensions?

The density of normal modes in 1D has already been discussed in another post (LINK) In essence, the formula is: $$D(\omega) = \frac{1}{2\pi}\int\mathrm{d}q\,\delta(\omega-\omega(q))$$ resulting in ...
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The d-orbital splittings in WS2 monolayer

According to this paper (and many others), the formely degenerate $d$ orbitals of the tungsten atoms in the $WS_2$ monolayer are split into three groups: (1) $d_{z^2}$, (2) $d_{x^2-y^2}, d_{xy}$ and (...
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Particle density in k-space

Question: Given a many particle wave function $|\Psi\rangle$, how can I calculate the occupation numbers in k-space? Setup: I have a 1D chain of molecules which contains 4 sites per unit cell. Let'...
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C libraries for Solid State Physics

During last year I've attended courses of solid state physics, and I studied methods for bands structure calculations in the Hartree Fock framework. However, I know only theoretical aspects of these ...
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1answer
50 views

Bands in semiconductors: $E$ vs. $k$ diagram

I always thought that in a semiconductor there was one gap, one conduction band and one valence band. However, reading a book I came across this picture And now I'm very confused. Apparently there ...
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1answer
44 views

Connection between fractional charge and Schrodinger's cat

In the FQHE, it is said that one electron splits into three 1/3-charged entities. Is it like the Schrodinger cat?
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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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At most $N$ gapless charge/spin modes in a system of $N$ coupled 1D chains?

Leon Balents and Matthew P. A. Fisher claimed the following without any further explanation ($N$ is the number of chains) For a system of $N$ coupled 1D chains, the number of gapless charge modes ...
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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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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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Why does Fermi Level change due to change in donor atom concentration?

Suppose I have a n-type semiconductor whose fermi-level lies (say) 0.2 eV below the conduction band. Why would this level change if I changed the doping by making the donor concentration (say) 4 times ...
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what is the physical significance of dielectric constant and loss tangent?

I want to know that the significance of dielectric constant and loss tangent behaviour. How it characterises the materials. and possible relation between the dielectric constant and polarisation ?
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Why the direct band gap semiconductor get higher optical absorption coefficient than indirect band gap semiconductor

I can understand that direct band gap semiconductor doesn't need phonon to absorb light. But in the following formula: Optical absorption coefficient is proportional to the square of hv in indirect ...
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1answer
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Is a typical glass slide really amorphous or does it just have very small crystallites?

I heard today that there's not really any true amorphous materials; that the theoretical concept (no level of ordering whatsoever) exists of course, but that no materials are 100% truly random and ...