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.

learn more… | top users | synonyms

0
votes
2answers
21 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 ...
1
vote
1answer
120 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 ...
0
votes
0answers
27 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?
0
votes
1answer
20 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 ...
4
votes
1answer
142 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 ...
1
vote
0answers
66 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 ...
1
vote
1answer
27 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 ...
0
votes
1answer
58 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 ...
0
votes
0answers
10 views

How does magnetic field leverage exchange interaction?

A 1 Tesla magnetic field corresponds to the energy of less than a millielectronvolt. However, fields of that order seem to saturate the magnetization of many solids, be they ferromagnets or ...
0
votes
1answer
48 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) \ ...
3
votes
1answer
80 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 ...
1
vote
1answer
19 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 ...
0
votes
1answer
42 views

how current is produced in semiconductors or metals?

I think current is 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. ...
2
votes
1answer
122 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?
1
vote
1answer
62 views

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 ...
1
vote
3answers
55 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 ...
2
votes
1answer
35 views

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) ...
1
vote
1answer
55 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 ...
3
votes
1answer
51 views

Why is graphene robust, but graphite not?

Graphite can be thought of as various layers of graphene mounted on top of each other. Graphene is known to be as robust as diamonds, yet graphite can be found in pencils and we all know from ...
4
votes
2answers
87 views

Proof that all primitive cells have the same size

A primitive cell of a crystal lattice is a set $A$ such that two copies of $A$ which are translated by a lattice vector do not overlap and such that $A$ tiles the entire crystal. I have read (for ...
2
votes
2answers
117 views

FCC lattice as a stack of triangular lattices

According to Marder, Condensed Matter Physics, Chapter 2: Within the planes normal to the vector [1,1,1], the atoms of an fcc lattice lie in a two dimensional triangular lattice However, he does ...
2
votes
2answers
62 views

Difference between adsorption and condensation

So I just stumbled across the Wikipedia article on adsorption - and I asked myself, if there is a difference between (physical) adsorption and condensation on a surface? When I look at the water ...
1
vote
0answers
29 views

Is there an intuitive reason for why the reciprocal lattice of FCC is BCC and vice versa?

This can be proved using formulae for generating reciprocal lattice vectors from direct lattice vectors. But does this result have more to it than meets the eye?
0
votes
1answer
51 views

How to prove Bloch function is periodic in reciprocal lattice?

How to prove Bloch function is periodic in reciprocal lattice? I saw in some textbooks this formula: $$ \Psi_{\mathbf{k}} (\mathbf{r}) = \sum_{\mathbf{G}} ...
0
votes
1answer
47 views

Why is temperature vibration?

Why do the atoms in a crystal vibrate at finite temperature?
1
vote
1answer
64 views

Can the Fermi level go above the conduction band energy if doped heavily enough?

So for n-type Si with donor density $N_d$ and donor energy level $E_d$, $N_d^+ = N_d(1+\frac{1}{1+e^{\beta (E_d - E_f)}/2})$ is the number of ionized donors, so we get an relation between the number ...
0
votes
0answers
33 views

Why is the k=0 phonon neglected when calculating Debye-Waller factor?

When calculating Debye-Waller factor one gets the form: $e^{-2W} = ...
0
votes
0answers
46 views

Effective mass vs. cyclotron mass of carriers (e.g. in graphene)

Since my original question (below) didn't get any answers (maybe it's to specific?), I'd like to rephrase to make it more general. What is the relation between the effective mass and the cyclotron ...
0
votes
0answers
24 views

Chemical potential and origin of pressure in a solid

Pressure of a gas is related to the rate of change of momentum of the particles; the temperature is the mean kinetic energy of the particles. Can the chemical potential be given a similar physical ...
2
votes
1answer
108 views

Goldstone modes of spin density wave

A spin density wave (SDW) is a phase in which a material suddenly shows a periodically modulated spin density $S_{\vec{q}}(\vec{r}) $ below a certain critical tempereature $T_C$. Obviously some kind ...
2
votes
1answer
48 views

Are the 14 Bravais lattices really distinct?

I have learned that there are 14 distinct Bravais lattices in 3D and any other thought lattice form could be reduced to or expressed in one of these 14 forms. But the primitive unit cell for f.c.c ...
0
votes
0answers
16 views

What are the possible reasons of deviation from Curie Weiss behavior well above Tc?

I think existence of other weak interactions which have higher transition temperature than the observed prominent interaction(ferro/antiferro) can perhaps lead to such result but I am confused when ...
2
votes
0answers
24 views

What material could be used to study magnetic phase transitions in a college laboratory exercise?

I am working to develop a simple laboratory exercise in solid state physics to be conducted by fourth year students of physics. The idea of the exercise is for the student to get some experience in ...
0
votes
1answer
25 views

Why is conductivity isotropic in a plane perpendicular to the z-axis of a tetragonal crystal?

Considering the symmetry of a tetragonal crystal, how can it be proved that conductivity is isotropic in a plane perpendicular to the z-axis?
1
vote
0answers
54 views

How to find dispersion relation for 1 d topological insulator?

Is it correct to write the dispersion relation for following Hamiltonian where $\sigma_{x}$ act in spin space and $\tau_{x}$ acts in pseudo spin particle hole spin $H_{BdG} (k)=(\xi_{k}+B\sigma_{x}+u ...
1
vote
1answer
69 views

$T$-invariant Hamiltonians

If $T$ is time-reversal transformation $t\mapsto -t$, Why do $T$-invariant Bloch Hamiltonians obey $$H(-k) = T H(k) T^{-1}$$ and not $$H(k) = T H(k) T^{-1}$$ Somehow I understand the word "invariant" ...
0
votes
0answers
55 views

Trace part of Hamiltonian

Given an electron in one discrete dimension, the Hamiltonian is given by $H_{n,n'}\in Mat_{N\times N}\left(\mathbb{C}\right)$ acting on $l^2\left(\mathbb{C}^N\right)$ where $N$ is some integer ...
9
votes
2answers
835 views

How quickly is motion transferred in a solid object?

Just for example: assume an iron bar one foot in length. If you push on one end, the entire bar will move. This seems instantaneous. but actually, from my understanding, the atoms all push against ...
4
votes
0answers
71 views

Is Differential Geometry used in Solid State?

I'm an undergraduate in physics interested in a career in solid state. While I know that any additional math is helpful--I am on time constraints, and can only take a few supplemental classes. That ...
0
votes
0answers
32 views

Dual order parameters of superfluid and Mott insulator

In this paper of Leon Balents, Matthew Fisher, Chetan Nayak, they mention the dual order parameters of superfluid and Mott insulator in 1D and 2D. There are some statements which (I suppose) ...
1
vote
0answers
20 views

What is the boundary of restorable thermal expansion?

As every book indicates, thermal expansion is a linear process $\frac{\Delta L}{L}=\alpha \Delta T$. Upon heating an object the result is thermal expansion. If we cool it down it is restored its ...
1
vote
1answer
31 views

Resistance of a diode in different regime and the physics of recombination current

I would like to ask question about the resistance of a diode under different regime. Surely, in reverse bias, it has a breakdown voltage, and in forward bias,it rises exponentially according to the ...
2
votes
1answer
39 views

neglect of lattice potential for conduction electrons

Why is it true that in nearly free electron compunds, complete neglect of the lattice potential is usually a good approximation as long as one considers crystal momenta remote from the boundaries of ...
1
vote
0answers
23 views

Charge density waves: site-centering v.s. bond-centering

Question about charge density wave (CDW): From this Ref. page 13, why bond-centering charge density wave is naturally compatible with the observed coexistence of charge ordering and ...
6
votes
2answers
173 views

Floquet and Bloch's theorems : connection?

It is often stated that Bloch's theorem and Floquet's theorem are equivalent, even the Bloch's theorem is often referred as Floquet-Bloch theorem. However, it seems quite confusing to me since the ...
1
vote
1answer
30 views

Why are crystals so useful for quantum isolation?

Some implementations of quantum gates (in the hopes of building a quantum computer one day) use crystals to isolate the qubits (to prevent decoherence). Why is a crystal so much better than an ...
0
votes
0answers
24 views

Spontaneous breaking order and the Peierls order

From this this Ref, several types of orderings are considered. Question: What are the Hamiltonians which support the Peierls order? Do they necessarily break translational symmetry or break the ...
1
vote
0answers
23 views

Nuclear spin relaxation, quasi-particle energy and spin spectral density

Below is a measurement of the longitudinal nuclear spin relaxation ($1/T_1$). Ref: Fig 4 of page 24 Competing ground states in low dimensions. My question concerns the statement in this Ref that: ...
2
votes
1answer
51 views

planewave Ansatz for modelling phonon dispersion in crystals

From Ashcroft's "Solid State Physics", for one-dimensional monatomic Bravais lattice, the equations of motion of ions are: \begin{equation} M\ddot u(na)=-K[2u(na)-u([n-1]a)-u([n+1]a)] \end{equation} ...
0
votes
2answers
56 views

What can we learn from a band structure diagram?

Other than the band gap and its magnitude, what are the things that we can immediately learn about the properties of the material just by glancing at its band structure? Can we say something about ...