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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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S-W correlation plot from positron annihilation Doppler broadening spectroscopy

From Doppler broadening spectroscopy, we get the S-parameter and W-parameter. I found a S-W correlation plot in many research papers. What information does this plot provide?
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Is there a noun for a material that absorbs, scatters and luminesces?

I know Luminophore is used for molecules or nanocrystals which absorbs and emit light, and Scatterer is used for materials which scatter light (elastically or inelastically). I suppose it would be ...
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Can there be quantum spin liquids in 1D?

It seems like everyone studies quantum spin liquids in either 2D or 3D. Can not there be quantum spin liquids in 1D?
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Magnetic field dependence of resistance

Experimentally, under the application of an external perpendicular magnetic field, we observe a change in the longitudinal resistance. However, in the theoretical development starting from the Drude ...
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Fermi level and chemical potential in doped and pure semiconductors

Recently I was studying about band theory of semiconductors and I have some questions. I found two definitions of Fermi level $1)$ The quantum state which has a probability of occupancy of $0.5$ (...
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Dipole moment in a bulk crystal

When calculating the dipole moment in a crystal, there is always one term neglected. This neglection is never discussed and I do not understand it at all. Assuming the Bloch functions $\Psi_{n,\vec{k}...
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What exactly is a coefficient of friction due to electron stopping?

To be more specific, I am looking to understand what electron stopping is and how I could possibly define a coefficient of friction due to electron stopping. I am running MD simulations using LAMMPS ...
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Electron-Hole in Spin-basis

A fellow student and I are arguing about the correct formulation of the hole in spin-basis, as the conjugate of the electron. Are the following correct: $\overline{|\frac{3}{2}, \pm \frac{1}{2} \...
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Feynman diagrams in quantum transport theory

I'm looking to find references that describe the role that Feynman diagrams play in quantum transport theory. I have heard discussions where it is possible to just insert a self-energy loop into an ...
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Can you argue without explicitly calculate the eigenenergies that one Hamiltonian is gapped and another is not?

Consider a pair of one dimensional four band model $H_1$ and $H_2$, which read as: $$ H_1 = \begin{pmatrix}k\sigma_x-E_0&0\\0&k\sigma_x+E_0\end{pmatrix} + \alpha \begin{pmatrix}0&\sigma_x\...
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Electrons' distribution inside bands

If you consider a crystal of silicon made by $N$ atoms, you know that there will be a valence band with $4N$ possible levels of energy for electrons and a conduction band with $4N$ possible levels of ...
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If $E$ and $P$ don't commute, why could we have an $E$-$K$ diagram?

If $E$ (energy) and $P$ (momentum) only commute in constant potential, how could we have an $E$-$K$ diagram in a solid material? $[E,p] \neq 0$. Then we cannot prepare electrons whose $E$ and $P$ are ...
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At null temperature, why an electric field would not allow an electron from the valence band to go in the conduction band?

With thermic energy (increasing the temperature), the electron can move from the valence band to the conduction band. With another source of energy, as the energy from a static electric field, why ...
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How important is quantum mechanics to solid state electronics? [closed]

How important is it to know quantum mechanics if one wants a career in solid state electronic devices? I want to do a PhD in semiconductor physics, but I don't know much quantum mechanics. What do ...
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Speed of sound in Aluminum given the debye temperature

I am trying to calculate the speed of sound in aluminum given the Debye temperature $\theta_D=428 \;\mathrm{K}$, the mass density of Al is $\rho = 2.7 \cdot 10^3 \;\mathrm{kg}\cdot \mathrm{m}^{-3}$, ...
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Geometrical proof of number of lattice points in 3D lattice

It is well known that number of lattice points in three-dimensional (3D) objects of simple cubic lattice, body-centered cubic lattice, and face-centered cubic lattice are 1, 2, and 4, respectively (...
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The polarization filter does not work

I am working in Conduction phenomena Photo-conductivity Experiment. Here the experiment guide . The aim is to measure the photocurrent $I_{Ph}$ as a function of the voltage $U$ at a constant ...
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Hall effect experiment [duplicate]

While studying the variation of hall coefficient with temperature for p-type semiconductor I found that after some time there is a change of sign of hall voltage on heating(it becomes -ve). What does ...
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Why can we use single electron Schrodinger equations to describe electrons in solids?

A solid is clearly a many electron system. Yet we often use single electron Schrodinger equations to calculate the quantities of interest. Probably this is most common in semiconductors. Why is that, ...
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Deriving the Heat capacity from Fermi-Dirac statistics

I was watching the lectures on Solid state physics by Steve Simon (Oxford). He was explaining how to find Heat capacity of metal due to electrons from Fermi-Dirac statistics. You can write the total ...
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What gives amorphous solids their solidity?

I understand that amorphous solids (like glass and plastic) don't have a symmetric lattice structure to their molecules or atoms, as do typical solids. It is often said that their molecules are ...
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What has coherence to do with this phenomena?

It reads,"Hardening due to coherent precipitate".Firstly,what has hardening to do with coherence of the precipitate?Why would dislocations shear the precipitate?
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Contact potential between metals

Metals Al and Au are connected in series. An ideal voltmeter, with both of its leads made of Cu, is connected across them. Then how come the voltmeter gives zero reading but why can't we measure ...
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Why is $\langle \text dp/\text dt\rangle$ zero for electrons in steady state?

While reading the Drude theory of transport in metals from the Oxford Solid state basics, I noticed when deriving the conductivity of the metal using Drude theory, to simplify the calculation the ...
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Tight binding model contradiction

I have been studying recently the tight binding model and there is a point I cannot understand. First, it starts from the idea that the electrons belong to the atom more than to the crystal, so they ...
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1answer
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Born van Karman periodic condition

Before getting deeper into the phonons. One of the conditions is that because of their quantization comes from the condition that system is invariant to translation. And length of the systems I can ...
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Creating a simulation of molecules

Just full disclaimer: I am a first year physics graduate student with very little experience in physics research. I would like to write to develop a toy model to teach myself a bit about spin ...
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Proof of Bloch's Theorem

I'm reading the book Solid State Physics by Ashcroft and Mermin. In its second proof of Bloch's Theorem on p.137, the periodic potential $U(\mathbf{r})$ and the wavefunction $\psi(\mathbf{r})$ both ...
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Integration domain of fourier series expansion on lattice

In solid state physics we define the Fourier expansion of a lattice periodic function $f$ as $$f\left(\vec{k}\right)=\sum_{\vec{R}_n} f_{\vec{R}_n} \mathrm{e}^{\mathrm{i}\vec{R}_n\cdot\vec{k}}$$ where ...
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How to differentiate b/w are lowest extended levels and highest extended levels in IQHE?

At low disorder there are three bands. Two side bands have one conducting state and the central band has two conducting state. I want to know that which states are lowest conducting states ?
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What is a non-local particle in condensed matter physics?

What exactly is "non-local" in physics? How can a particle be non-local particle? Are non-local particles and collective modes related with each other? Are solitons local or non-local? (I am asking in ...
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Low energy continuous model to lattice model(tight binding) in solid physics state

It is widely employed to link the low-energy continuous model to lattice tight-binding model using this strategy as shown in Section IIA Page.1063 of RMP 83, 1057 : Just replace $k_i$ by using $\frac{...
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Questions about unitary condensate wave-function and $p_x+ip_y$ superconductor

I read about the unitary and non-unitary order parameter states here https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.75.657 and https://arxiv.org/abs/1512.01151 The form of the order ...
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Gauge transformation for Bloch waves?

I have seen in many places saying a gauge transformation transform the Bloch wave function as $\psi_{nk}\to e^{-i\phi_n(k)}\psi_{nk}$. However I don't quite understand how it is related to the "gauge ...
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Correct my view of energy levels in universe?

Kindly apologize me if I am sounding very naive and wrong. I am very new to the field of solid state physics. I am having this question in my mind. We know that a solid has energy levels for electrons ...
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Number of electrons within Fermi Surface

This question is regarding problem 9.5 in Ashcroft and Mermin where we have to calculate the radius of the Fermi circle in a 2D square lattice with lattice constant $a$ and $m$ electrons per primitive ...
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Meaning of electron displaced to another quantum state in another location

For example, in a p-n junction scenario where the electron is displaced from LOCATION A, due to diffusion to a lower quantum state at LOCATION B in the p-type silicon, as seen in the following diagram ...
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How to get the energy bands of the Haldane model?

I am struggling with how to get the dispersion relationship of the Haldane model and plot it, just like this: And then apply it to graphene nanoribbons (armchair) and plot it like this: Here's a ...
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A fast and automated way to check if symmetry (space group) operations preserve a lattice

Consider the simple cubic lattice. There are symmetry operations which preserve the lattice symmetry such as translations and rotations around certain axes. There are also symmetry operations that do ...
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Crystal lattice Fourier coefficient

In solid state physics we have a periodic function over the lattice as $$f(\boldsymbol{r})=\sum_{\boldsymbol{G}}f_{\boldsymbol{G}}\mathrm{e}^{2\pi i\boldsymbol{G}\cdot\boldsymbol{r}}$$ where $$\...
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Solar cell: Surprising change in EL for varying PEDOT:PSS-thicknesses

I am currently working on improving a solar cell, which is partly transparent and therefore utilizes two transparent electrodes (TCO on top and PEDOT:PSS on the bottom). As PEDOT:PSS alone is not ...
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How to calculate optical conductivity from numerical eigenstates of tight-binding model?

Let's say we have a 1D spatially inhomogeneous tight-binding model that does not have momentum as a good quantum number. We can numerically diagonalize it to get the spectrum and eigenstates. But how ...
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1answer
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Why do we have to introduce quasiparticles in the Fermi liquid theory

Why is it necessary in Fermi liquid theory to introduce quasiparticles? I understand the notion of system where someone can turn on the interactions slowly (i.e., adiabatically), but I do not ...
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Why is silicon absorbing visible light?

Here it is shown that silicon absorbs visible light: but the band gap energy for direct transitions is 3.6 eV which does not match to this absorption coefficient. Instead, the band gap energy for an ...
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What is the effects on the electrical conductivity of a crystal structure if the Fermi sphere fits inside the first Brillouin zone

My explanation: If the Fermi sphere fits inside the first Brillouin zone then there are empty states between the 1st and 2nd Brillouin zone which electron can be excited into. Hence, the crystal ...
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Is there a physical meaning of the Fermi liquid parameters

In Fermi liquid theory we define two parameters $F_l^s = VN(\epsilon_F)u_l^s$ and $F_l^a = VN(\epsilon_F)u_l^a$ where V is the fermi-volume, $N(\epsilon_F)$ the density of states at the Fermi energy ...
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Can we study the effects of Quantum reflection on heavy atoms?

From what I've looked at, it feels like QR has only been studied on light atoms like He, Ne, Na, H, etc. But can we study this effect on heavy atoms like Rb-87. If not, is it because of the ...
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Plateaus in Quantum Hall effect

Why do the plateaus in the Quantum Hall Effect appear phenemenologically? Something to do with the 1D transport for the edge states?
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Eigenvalues of Bose-Hubbard model

I want to see eigenvalue spectrum of Bose-Hubbard Hamiltonian. Can anyone send me the algorithm to write Bose-Hubbard Hamiltonian.
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How does this quantity transform under time reversal and inversion operation respectively?

Suppose $\psi_{nk}=e^{ikr}u_{nk}$ is the Bloch function of a periodic Hamiltonian $H(r)=H(r+R)$, where $H(r)\psi_{nk}=\varepsilon_{nk}\psi_{nk}$ and $H(k)=e^{-ikr}H(r)e^{ikr}$. What would the ...