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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Resonant vs. Non-resonant Raman

What does it mean to say that the conventional Raman effect is non-resonant? And, how/why does resonant Raman give a stronger signal than the non-resonant type?
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Hamiltonian for semiconductor

I was wondering which terms we need in a semiconductor Hamiltonian where no transition between the valence and conduction band occur? First we would have a term describing the energy of the full ...
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163 views

Interpretation of Fermi-Dirac statistics

I was reading that as temperature increases the energy at which $n(E)=0.5$ shifts to lower energies as these lower energy states become depopulated. Could someone explain that, what it means and why ...
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68 views

Capacitor of Pearson–Anson oscillator

I was calculating capacitance of Pearson–Anson oscillator and comparing with simple RC circuit but I get two different values. They have significant difference. I am not clear why do they have. Could ...
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53 views

Integrals in tight-binding method

In the tight-binding method, as e.g. described in Ashcroft and Mermin one need to solve a few integrals in order to proceed. For example for the overlap between an orbital situated at two different ...
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118 views

Energy conservation of permanent magnets engine

How to explain the fact that magnet can attract an object (apply a work W) without losing a (significant) part of its internal energy? How to apply the energy conservation principle? Please think to ...
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210 views

How holes conduct current?

I had questions about holes in semiconductor, when i checked the net it is said holes are said to be equivalent positive charge and they say because the hole moves from one place to another when it is ...
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86 views

How to derive De Haas–van Alphen effect?

I was reading Solid State Physics by Kittel and they manage to derive De Haas–van Alphen effect by invoking the Bohr-Sommerfeld model. This feels unsatisfactory to me. Can someone derive this using ...
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45 views

Is it possible to get the (Pauli) repulsive term in the Lennard-Jones potential from theoretical considerations?

Title says it: Is it possible to get the form of the (Pauli) repulsive term in the Lennard-Jones potential from theoretical considerations, or is it purely found experimentally through fits?
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222 views

Tight binding in the limit of large system size

Suppose that one has a continuous Hamiltonian with spin-orbit interaction, for example $H=-\dfrac{\mathbf{p}^2}{2m} +\kappa({\boldsymbol\sigma}\times\mathbf{p}) + U(x)$ and want to approximate this ...
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223 views

What kinds of behavioural anomalies can a zero-field-cooled (ZFC) / field-cooled (FC) split indicate?

If a material shows a spiltting in the ZFC and FC curves, is it necessarily superparamagnetic, or could there be any other reason for the irreversibility? I have heard spin glasses also show ZFC-FC ...
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30 views

What exactly is cutting with a knife will look like on the atomic scale? [duplicate]

Some times I like to view the world in the microscopic scale .ie. at this level all objects any thing will be collection of atoms which we normally don't view with our naked eye. At that scale I ...
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64 views

How does the saturation current of a heterojunction depend on on the band gap difference?

In my textbook, they demonstrate that, for a regular n-Si/p-Si pn junction, the electron saturation current density (it's pretty much the same for the holes, but with hole properties instead of ...
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63 views

Why are holes (in a semi conductor) regarded as particle?

Can I say that holes in a semiconductors are treated as current-carrying conventional direction ?
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57 views

Coulomb repulsion in the Anderson impurity model

In Phil Anderson's famous paper on impurities, Localized Magnetic States in Metals, he has the following paragraph on page 44, However, I am puzzled by the last sentence: why is the $J$ part ...
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228 views

Question about electron-hole pair generation in depletion layer for a p-n junction photodiode

At the heart of operation of p-n (or p-i-n) junction photodiodes is the absorption of photons leading to generation of electron-hole pairs. If the diode is, e.g., reverse biased, then the motion of ...
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66 views

Reciprocal to determine Miller indices

If we know the reciprocal space basis of a BCC lattice \begin{align}b_1=\frac{2\pi}{a}(\vec{x}+\vec{y}),b_2=\frac{2\pi}{a}(\vec{z}+\vec{y}),b_3=\frac{2\pi}{a}(\vec{x}+\vec{z})\end{align} how do we ...
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170 views

How to obtain the asymptotic behavior of Green's function?

This question arose from Eq.(9.135) and Eq.(9.136) in Fradkin's Field theories of condensed matter physics (2nd Ed.). The author mapped quantum-dimer models to an action of monopole gas in $(2+1)$ ...
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54 views

Bulk modulus as a function of $U(r)$ at equilibrium

PART I The Bulk modulus equation $$B=-V\left(\frac{\partial P}{\partial V}\right)\tag{eq 1}$$ can be transformed into a similar equation as a function of $r$ (interionic equilibrium distance in a ...
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97 views

Bulk Modulus as a function of U and V for fcc lattices

Original bulk modulus equations is $$B=-V\left(\frac{\partial P}{\partial V}\right)\tag{eq 1}$$ At isothermic processes $$P=-\frac{dU}{dV}\tag{eq 2}$$ We can write B in terms of the energy per ...
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136 views

Bulk Modulus and its derivative for a fcc lattice

The bulk modulus $B = - V \left(\frac{\partial P}{\partial V}\right)$. At constant temperature the pressure is given by $P= -\frac{\partial U}{\partial V}$, where$ U$ is the total energy. We can ...
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38 views

Definition of a semiconductor

Originally I had learned that solids are split into two categories: isolators/semiconductors, and metals. The fundamental difference between the two is the existence of a bandgap. Metals don't have ...
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Thermal conductivities of the phonon and electron gases

From my lecture notes I have the following relations: High Temp: Phonon gas $\kappa \propto 1/T$ Electron gas $\kappa \propto 1/T$ Low Temp: Phonon gas $\kappa \propto T^3$ Electron gas $\kappa ...
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Does it make sense to define the mean free path in quantum mechanics?

The mean free path defined in classical molecule dynamics has a strong classical flavor. Is it sensible to generalize the idea to quantum mechanics?
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Can one calculate the electric conductivity of iron?

Iron is a commonplace material. It is common knowledge that it conducts. Is it possible to accurately calculate the electric conductivity of iron? With what kind of method? Up to what precision?
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116 views

scaling theory of Anderson localization

Initially, Anderson studied the eigenstates of the tight-binding Hamiltonian $$ H = \sum_n \epsilon_n a_n^\dagger a_n + V \sum_{m,n} a_m^\dagger a_n . $$ His question was whether the eigenstates ...
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Why is Terahertz radiation so hard to generate?

This paper (and many others I've read) claim that searching for ways of producing THz radiation is a high-interest research topic. However, something I've just never understood is why it's so hard ...
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118 views

Why is the density of states in k-space constant?

Why are the allowed states in k-space equidistant in every direction? As a consequence of this, a DOS of $\frac{V}{(2\pi)^3}$ is obtained in 3D for phonons, $2 \cdot \frac{V}{(2\pi)^3}$ for electrons ...
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21 views

Vortex-domain wall co-excitation

Both vortices (or disclinations) and domain walls are possible topological defects in a spin system with frustration, but I did't find reference about the interaction of these two. Do any stackers ...
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92 views

Measurement of the dispersion relation in a crystal: Inelastic neutron scattering

Is the analyzer in the thees axes spectrometer just another monochromator? If we can measure the energy of the neutrons after scattering with a detector, why do we need the analyzer?
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31 views

Mott's conjecture about NiO verified or not?

Mott in his 1949 paper, said: ''On the view explained above, therefore, if a substance such as NiO were subjected to very high pressure it should suddenly show metallic conduction for some value of ...
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76 views

What are the Fermi and Debye temperature constants?

What are the Fermi temperature and Debye temperature constants? We were discussing these in class and I don't fully understand what these constants are or why we have them. Can anyone explain?
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52 views

What do we get from the diagonalization of the $k\cdot p$ matrix?

In k.p theory, we expand the wave function around a known point ${\bf k}_0$ $$u_{\lambda}({\bf k})=\sum_{\nu} c_{\lambda,\nu}({\bf k})u_{\nu}({\bf k}_0).$$ If we now consider 8 bands (conduction, ...
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39 views

What is an off-axis peak in x-ray diffractometry?

I'm looking at a $\theta$ - 2$\theta$ pattern of my thin film which in bulk is cubic (bcc) and I see 001 and 002 peaks of the film. There is supposed to be a tetragonal distortion meaning that I need ...
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165 views

What intermediate steps of the Dirac Delta Function and Fourier Series am I missing in finding a solution to the Kronig-Penney Model?

Intro We're looking at the Kronig-Penney model in class and one of the conundrums is related to the Kronig-Penney potential for a chain of $N$ atoms. I'm supposed to squeeze out some expression for ...
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81 views

How far away are we from a UV LED operating at around 100nm?

So far, we are down to around 250nm for UV LEDs. If I could get one at around 100nm that would ionize air I would find it very useful. Any ideas on whether this wavelength is feasible for a LED?
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73 views

Silicon: conduction band minima

Why do the energetic minima of the silicon conduction band lie not in a high-symmetry point like a $X$-point, but somewhere in $\Delta$-direction between points $\Gamma$ and $X$? What is the physical ...
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236 views

Can ice freeze? [closed]

We know that ice is already the frozen (solid) form of water. The question is more like: Can this frozen form freeze further? Or can it become more solid? (for example, by exposing to colder ...
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559 views

Peierls substitution vs minimal coupling

In the presence of vector potential (let's assume it's uniform), a tight-binding Hamiltonian will be changed according to the Peierls substitution: $$t_{ij}c_i^{\dagger}c_j \to ...
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36 views

Multiple Bandgaps

I'm going through solid state physics' models chronologically and I've reached the Bloch theory, which is after Sommerfeld's quantum mechanical version of the Drude model with an added infinitely deep ...
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129 views

Density of state vs energy

Please bear me for this naive question. In the definition of density of state in 3D we know that DOS $\rho(E)$ varies as $E^{\frac{1}{2}}$ i.e as energy increase it should increase. But when I see ...
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114 views

Quantum Theory of Paramagnetism

The energy levels of the system in a magnetic field are $$ \ (1) \ U=-\vec \mu \cdot \vec B$$ As per the Kittel's Solid State physics which has confused me since, Now, $$ \ \ \ \ \ (2) \ ...
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345 views

Why is Bose-Einstein condensation a phase transition?

Bosons may succumb to a Bose-Einstein condensation at a certain critical temperature $T_c$, thus entering the BEC phase. The only thing I know about the BEC is that since we are talking about bosons ...
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50 views

Device design regarding recombination mechanisms

While in a LED radiative recombination is desired, in a solar cell no type of recombination is favourable. How are the different recombination mechanisms controlled? SRH is pretty straightforward ...
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415 views

How is current produced in semiconductors or metals?

I think current is the movement of electrons through the wire or semiconductor, thus when I press the switch of the light bulb the electrons go from positive part to tungsten and light is produced. ...
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180 views

Why does a half filled Brillouin zone result in conductivity?

As stated in the title, why does a half filled Brillouin zone result in an element being a conductor, or conversely, why does a filled Brillouin zone result in an insulator?
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Need help visualizing a conceptual problem; solid mechanics 1

When the instructor posed this problem to the class, no one could answer the question because we all had difficulty 'seeing' what was happening. I get that because they're different materials, the ...
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102 views

Why are $2\pi$ factors included in the definition of the reciprocal lattice?

I would like to know where the $2\pi$ factors are coming from in the formula for reciprocal vectors in reciprocal lattices. For example, in a simple cubic lattice the primitive vectors are given by ...
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Intuitive explanation for the space-dimension dependence of the density of states of a free electron gas

If the Schrödinger Equation is solved in different dimensions for an independent electron in an infinitely high potential, different relations are obtained regarding the DOS. These are: 0D: $D(E) ...
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332 views

Work function definition

As in this post How would I calculate the work function of a metal, the definition is given by "the minimum thermodynamic work (i.e. energy) needed to remove an electron from a solid to a point in the ...