What is Hall effect: Definition and 131 Discussions
The Hall effect is the production of a voltage difference (the Hall voltage) across an electrical conductor that is transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current. It was discovered by Edwin Hall in 1879.A Hall effect can also occur across a void or hole in a semiconductor or metal plate, when current is injected via contacts that lie on the boundary or edge of the void or hole, and the charge flows outside the void or hole, in the metal or semiconductor. This Hall effect becomes observable in a perpendicular applied magnetic field across voltage contacts that lie on the boundary of the void on either side of a line connecting the current contacts, it exhibits apparent sign reversal in comparison to the standard ordinary Hall effect in the simply connected specimen, and this Hall effect depends only on the current injected from within the void.Superposition may also be realized in the Hall effect: Imagine the standard Hall configuration, a simply connected (void-less) thin rectangular homogeneous Hall plate with current and voltage contacts on the (external) boundary which develops a Hall voltage in a perpendicular magnetic field. Now, imagine placing a rectangular void or hole within this standard Hall configuration, with current and voltage contacts, as mentioned above, on the interior boundary or edge of the void. For simplicity, the current contacts on the boundary of the void may be lined up with the current contacts on the exterior boundary in the standard Hall configuration. In such a configuration, two Hall effects may be realized and observed simultaneously in the same doubly connected device: A Hall effect on the external boundary that is proportional to the current injected only via the outer boundary, and an apparently sign reversed Hall effect on the interior boundary that is proportional to the current injected only via the interior boundary. Multiple Hall effects superposition may be realized by placing multiple voids within the Hall element, with current and voltage contacts on the boundary of each void. DE Patent 4308375
The Hall coefficient is defined as the ratio of the induced electric field to the product of the current density and the applied magnetic field. It is a characteristic of the material from which the conductor is made, since its value depends on the type, number, and properties of the charge carriers that constitute the current.
For clarity, the original effect is sometimes called the ordinary Hall effect to distinguish it from other "Hall effects", which may have additional physical mechanisms, but build on these basics.
I understand that the Quantum Hall Effect explains how both the transverse and longitudinal resistance vary with magnetic field strength.
I don’t get why the hall resistance is equal to the hall voltage over the current .
I know current isn’t a vector quantity but isn’t the hall resistance an...
I am studying Berry curvature for a specific material and faced different types of the Berry curvature formula. Some papers use only valence eigenstates (u1) like this
i∗(<(∂U1/∂kx)|(∂U1/∂ky)>−<(∂U1/∂ky)|(∂U1/∂kx)>)
and someone uses summation on all the conduction and valence bands like this...
A current carrying conductor experiences magnetic force in a magnetic field.
F=BILsinθ
Where, B = Magnetic flux density
I = Current
L = Length of conductor and
θ = Angle between magnetic field and current
This force is due to free electrons moving in a...
My first assumption is that the temperature dependence on the mobilities can be neglected, and so we would have:
$$R_H(T)= \frac{1}{e} \frac{p_v(T)\mu_h^2-n_c(T)\mu_e^2}{(p_v(T)\mu_h+n_c(T)\mu_e)^2}$$
The expression for the electron and hole densities could be derived from...
so with a Hall Voltage, you have positive current traveling upwards in a wire in the +y-direction and a magnetic field into the screen in the -z-direction. the right hand rule has positive charge deflecting to the left. now if you look at the drift velocity of electrons moving downward in the...
This is the diagram provided in the question:
The ring is made of conducting material. I was originally asked to find the potential difference between ##a## and ##b##. I did so using the Hall effect (and assuming it would work as per normal in this situation). This got me ##\Delta V = vBl##...
Hello there, I am having trouble understanding what parts b-d of the question are asking. By solving the Schrodinger equation I got the following for the Landau Level energies:
$$E_{n,k} = \hbar \omega_H(n+\frac 12)+\frac {\hbar^2k^2}{2m}\frac{\omega^2}{\omega_H^2}$$
Where ##\omega_H =...
Hi!
Reading through this paper, the Hall resistivity in ferromagnetic materials is given by $$\rho_H = R_0 B + 4 \pi R_s M$$
It is mentioned that ##R_s## (anomalous Hall coefficient) is significantly larger than ##R_0## (ordinary Hall coefficient) and has a strong dependence on temperature...
Hi!
I'm trying to understand the dependence of spin hall voltage on various parameters of the material. I have been going through this paper, and it is mentioned that $$V_{SH} = 2 \pi R_s L j_x n \mu_B$$
In the equation, only ##L## and ##j_x## seem to be the variables. Does increasing ##L##...
Circuit runs from q0 to q1, some E field (our charge source/sink)
1. Is the current running from q0 to q1 impacted by the existence of the B field? For example, if there were no B field, current would flow from q0 to q1, let's call it I0. When we flip on the B field what effect is there on the...
How does the Hall effect work in semiconductors. Since the there aren't enough availabe energy states in the valence band to hold all electrons trying to move due to the magnetic field the Hall effect must be weaker correct?
Could anyone please explain the differnce between these two picture of Ashcroft & Mermin solid state physics book:
Why in these two pictures the + and - signs don't compatible with each other?! I think in the pic12-11 the signs don't draw correctly. It must be vice versa I mean + signs in left...
In the ch1 if solid state physics Mermin & Ashcroft, in the hall effect section these paragraph are about cyclotron frequency, but what the two last terms want to say(the screen shot of the page is attached)? And I can't understand what happens to hall constant in high-field regime?
A current is flowing in a copper wire (electrons are flowing). The electrons will be deflected to the left wall of the wire due to Hall effect. They leave on the right wall of the wire a deficit of electrons, leaving them positively charged, so there’s a voltage difference between the left and...
I have read some materials about quantum hall effect and know that at the edge of a 2D material , one can linearize the potential V and the linear dispersion relation represents right/left moving fermion. So , Can I say that for a given hamiltonian , if I can linearizae it at edge, then this...
Hello there,
I don't really get the difference between the extrinsic or intrinsic spin hall effect or contribution. As i understand, in extrinsic you have spin scattering by impurities, so its the spin orbit interaction of the spin with its orbit, and this orbit is influenced by an impurity...
Hi, I'm looking at QHE notes D.Tong and wondering how he gets from equation 5.46 to 5.48 ( http://www.damtp.cam.ac.uk/user/tong/qhe/five.pdf )
##S_{CS}=\frac{k}{4\pi}\int d^3 x \epsilon^{\mu \nu \rho} tr(a_{\mu}\partial_{\nu}a_{\rho} -\frac{2i}{3}a_{\mu}a_{\nu}a_{\rho})##.
manifold ## \bf{R}...
Hello everybody,
Im looking for a good explanation for the Rashba effect or Rashba Spin Orbit coupling (when it is the same effect with 2 names?) . If somebody can help me here that would be awesome. Moreover i try to understand the intrinsic mechanism of the Spin Hall Effect with the Berry...
Hi , I'm looking at the argument in David Tongs notes (http://www.damtp.cam.ac.uk/user/tong/qhe/three.pdf) for ground state degeneracy on depending on the topology of the manifold (page 97, section 3.2.4).
I follow up to getting equation 3.31 but I'm stuck on the comment after : ' But such an...
Hello guys,
I am building a small prototype for a Coolant Dispensing System and need to measure the flow rate of water & chemical in the pipe in order to control the opening of valves downstream.
Since I am building a small pilot system, I can't really spend too much money and hence I intend...
Where does energy come from in potential difference appearing in Hall effect?It is magnetic force causes this potential.But we know that magnetic force does not do work on motion charge particles, then where is the energy come from?It seems contradiction that magnetic forces cause the potential...
Greetings,
assume we have a 2-dimensional system in the x-y-plane. An electric field is applied in x-direction, a magnetic field is applied in z-direction. As is well-known, the charge carriers get pushed in the y-direction due to the Lorentz-force until the Hall field is strong enough to...
In my textbook, it is talking about the Hall Effect on a flat conductor with width w carrying a current i in a uniform magnetic field perpendicular to the plane of the strip. It says that this will create a potential difference of V=E/w where E is the induces electric field from the electrons...
Hi! I had this problem for homework (Mastering Physics), and I'm not sure what I'm doing incorrectly. Is there something fundamental that I'm misunderstanding? Each time I do this, I get 0.717136.. T as my solution
1. Homework Statement
I = 12.6 A
w = 0.0142 m
t = 0.00122 m
E_H = 1.82 *...
Many times, the charge carrier density of a material is determined from a Hall effect experiment, from ##R_H=1/(ne)## (SI units). Where ##R_H## is determined from a measured voltage and other controllable parameters. As far as I know, this simple formula comes from the obsolete Drude's model...
I'm reading Mermin's Solid State Physics, chapter 12: The semiclasssical model of electron dynamics. I know the current density from the ##n## band is
$$ \mathbf{j}=(-e)\int_{\text{occupied}}f(\epsilon_{\text{n}}(\mathbf{k}))\frac{d\mathbf{k}}{4\pi^3}\mathbf{v}_{\text{n}}(\mathbf{k}). $$
In...
(Oh my god, why can't my post show normally? Some sentences just disappear, but I can still see them while editing. It's very weird. Can someone help me? I've reported.)I know only partially filled bands result in current density, and I think there must be not only 2 partially filled bands, but...
Hey,
I read about charge carriers in semiconductors in a magnetic field.
They write that for several revolutions ##\omega_c \tau >>1## holds.
But I think for one revolution it is ##\omega_c \tau = 2 \pi##.
(##\tau## is the scattering time)
Why they do not write ##\omega_c \tau >> 2 \pi##...
Homework Statement
Homework Equations
3. Solution
Then the equations from part (A) are used--but why does the converted trig (1-cos(etc)) go away?
Does this have to do with the mean-squared bit?
Hi, in laboratory i had a sample of Ge with p-doping. In a first place i have done different measure V vs I (first image)
Then i insert the sample in a magnetic field perpendicular to the sample.
And i have done measure of V vs B (with a fixed current at 8 mA) and i obtained the second image...
Hi,
I have been trying to understand how the spin hall effect comes about. However, everywhere I look I just find 'the spin-orbit interaction couples the charge and spin current'. I really don't understand how does the current couple through the interaction. Any help would be much appreciated...
Since the classical Hall EMF is proportional to current, in an alternating current circuit, the Hall Emf should also follow an alternating pattern. Is it so? Or the Hall Emf doesn't change in a sine wave pattern instead remains more or less same and has a voltage based on the average/rms...
For a lab I just finished this past week, we were working with the hall effect and finding hall voltages. The metals used were p-germanium and n-germanium semi-conductors. I understand why in n-germanium the hall voltage is positive and p-germanium is negative assuming negative charge carriers...
Hi,
does anybody know of any good sources to learn about the Integer Quantum Hall effect from the perspective of theoretical physics?
Any suggestion will be appreciated, thanks.
I want to test the accuracy a linear displacement sensor (Hall effect) that I have, but I'm not sure what to measure it against. The sensors are made to measure with a resolution of 10μm. My initial thought was to use a drill press to move up and down, but I don't think I know of any that are...
I want to record the displacement of a small magnetic ball moving sideways across the face of the sensor. I've had a close look at AMS's catalog of magnetic position sensors and I'm not sure how to choose one.
If I'm working with a movement range of <5mm and want a resolution of 5-10μm, and...
I have studied the integer quantum hall effect mainly from David Tong's notes and i understand how the ## \rho_{xy}## is quantized in terms of the chern number. What I don't understand is
- how the chern numbers relate to the number of filled Landau levels though.
- I also don't understand the...
I have read some paper about transport measurement of graphene.
From classical hall effect, we can get some information about kind of charge carrier, charge density etc.
So, it is important for understanding matter.
But, I don`t know why quantum hall effect is important in graphene transport...
Homework Statement
The problem asks to find the Total Force on the Circuit Loop. I have a circuit loop with length 30.0 cm and width 10.0 cm with a current I2= 30.0 A that is flowing counter-clockwise. There is a wire that has the current I1=15.0 A flowing from left to right and is 7.50 cm from...
I have a good understanding on the hall effect. However, I was told by my tutor that the electric field direction at equilibrium remains pointing in the negative side of the conducting material and the force it generated is canceled out. But further reading online text, the electric field...
There are lots of measurements showing strong temperature ($T$) dependence of Hall coefficient ($R_H$) in correlated materials (eg. cuprate superconductors and other oxide materials) and such plots are available in many recent experimental papers. However, I could not find any $R_H$ vs $T$ plot...
Homework Statement
A metallic film has length L=10mm, width W=1mm and thickness t=1##\mu m##. The current is parallel to the long edge and has magnitude ##I=0.7A##. Longitudinal voltage is ##V=1V## and it doesn't change with magnetic field. The Hall (transverse) voltage ##V_H## increases at...
Been thinking to make a quadcopter, not a huge one, a fairly small and light one to start out with. The problem is I would like it to read the RPM of each engine separately.
There are several ways I have came up with:
- One of them is to use the current reading and calibrate it, however using...
I've been reading the explanation of Britannica.com about the direction of magnetic force on a moving charge in hall effect.
"Whether the current is a movement of positive particles, negative particles in the opposite direction, or a mixture of the two, a perpendicular magnetic field displaces...
A slab made of unknown material is connected to a power supply as shown in the figure. There is a uniform magnetic field of 0.7 tesla pointing upward throughout this region (perpendicular to the horizontal slab). Two voltmeters are connected to the slab and read steady voltages as shown...
Suppose I have an n-doped semiconductor and want to measure the electron concentration in the conduction band as a function of temperature.
How would I go about doing this by measuring the Hall coefficient as a function of temperature, given that I don't know the electron and hole mobilities...
Homework Statement
Lets say we have two horizontal rails connected by a resistor to the left, and we have a movable conducting rod that slides without friction on the rails.There is a uniform magnetic field going into the page.
Homework Equations
F = ILB[/B]The Attempt at a Solution
Now, I...