The underlying principle of this phenomenon is a change of the current path in the hybrid structure upon application of a magnetic field, due to the lorentz force. Their faraday rotation can be up to six orders of magnitude higher than that of nonmagnetic semiconductors. In this dissertation, the extraordinary magnetoresistance emr effect in semiconductormetal hybrid structures is studied to improve the performance in sensing applications. Magnetism and semiconducting properties are known to coexist in some ferromagnetic.
Magnetoresistivity can now depend on magnetic field, angle, and. The silicon becomes an ntype semiconductor because of the addition of. The semiconductor materials used in electronic devices are doped under precise conditions to control the concentration and regions of p and ntype dopants. The transverse magnetoresistance of the inmnas layer was measured in magnetic fields up to 1 t and in the temperature range of 1961 k. Magnetic field can also be used to cause the metal to semiconductor transition, a phenomenon also called colossal magnetoresistance. Anisotropic magnetoresistance in an antiferromagnetic. Magneto resistor is a type of resistor whose resistance changes when an external magnetic field is applied. Universal properties of linear magnetoresistance in strongly disordered mnasgaas. We are going to treat the magnetoresistance of metals in a quite general and simple manner. You will 1 measure the temperaturedependence of resistivity, 2 determine the energy gap e g, and 3 study the hall effect. The fifth electron becomes a conduction electron that is donated to the conduction band.
The magnitude of the effect in materials used in the recording industry has. Semiconductors with electric and magnetic properties. Ferromagnetism and giant magnetoresistance in zincblende. Magnetoresistance effects in hybrid semiconductor devices citation for published version apa.
Hall coefficient and transverse magnetoresistance of narrow. In other words, the flow of electric current through the magneto resistor changes when an external magnetic field is applied to it. Hall coefficient and magnetoresistance of semiconductors. Giant room temperature magnetoresistance in singlecrystal femgofe magnetic tunnel juctins, nature vol. There are a variety of effects that can be called magnetoresistance. Today, highly integrated semiconductor detector systems with tens of thousands of. Plots of magnetoresistance versus magnetic field at four different temperatures are shown in. Issues in colossal magnetoresistance cmr manganese oxides. Dowell associate professor of electrical and computer. Magnetoresistance and hall effect in the ferromagnetic semiconductor ga1xmnxas k w edmonds, r p campion, ky wang, a c neumann, b l gallagher, c t foxon, p c main school of physics and astronomy, university of nottingham, nottingham ng7 2rd, uk abstract. If implemented in devices, these materials could provide a new type of control of conduction. Magnetoresistance of inmnas magnetic semiconductors.
The dependence of the magnetoresistance on applied magnetic field will be determined and compared to theoretical predictions. Magnetoelectronics at edges in semiconductor structures. Very large tunneling magnetoresistance in layered magnetic. Magnetoresistive angular sensors nxp semiconductors. Magnetoresistance an overview sciencedirect topics.
Magnetoresistance definition of magnetoresistance by. In a thought experiment in free space, another observer, attached to frame o x,y,z, moves at velocity v c2. Here, we designed a modified semiconductormetal hybrid device with i v i v i configuration, where i and v represent current lead and voltage probe. Magnetooptical devices for optical integrated circuits. It is shown that in a weak magnetic field the transport coefficients exhibit non.
The element which has these effects is known as the magnetoresistor. In the late 1940s the invention of the transistor was the start of a rapid development. The resistance of some of the metal and the semiconductor material varies in the presence of the magnetic field, this effect is called the magnetoresistance. Using twodimensional finite element simulations, the geometric dependence of the output sensitivity, which is a more relevant parameter for emr sensors than the. Nxps magnetoresistive angular sensors, by using a true angular measurement, approach work accurately and reliably with no magnetic field strength variations. Whereas traditional electronics are based on control of charge carriers nor ptype, practical magnetic semiconductors would also allow control of quantum.
Based on ab initio calculations, we associate the origin of the phenomenon with large anisotropies in the relativistic electronic structure. This vlmr occurs when the electrons occupy the open fermi surface and their motion. Semiconductors are good for testing theory because they offer another dimension for measuring resistivity. Matthew melissa physics 141a spring 20 1 giant magnetoresistance matthew melissa april 4, 20. In other words, the magnetoresistor is a type of resistor whose resistance varies with the magnetic field. But the garnetmade isolators have not been monolithically integrated with semiconductor optoelectronic devices, because these oxide crystals can not be grown on semiconductor substrates. To observe the phenomenon of magnetoresistance in a semic onductor and study the magnetic eld dependence of the transverse magnetoresistance of a given semiconductor sample. The x is a crossproduct, which means that the magnitude size of the force is found from. Magnetoresistance of semiconductormetal hybrid structures.
Vertical longitudinal magnetoresistance vlmr caused by the peculiar shape of the fermi surface of a superlattice has been observed in gaasalxga1xas superlattices. Paramagnetic semiconductor cd 1x mn x te is promising as a magnetooptical. Marius grundmann the physics of semiconductors fulvio frisone. Important to practical applications is the fact that the geometry of a semiconductor sample can generate very large magnetoresistance, as in the corbino disk. Magnetoresistance and hall effect in the ferromagnetic. Ravindran, phy02e semiconductor physics, 30 january 20. Magnetoresistance definition is a change in electrical resistance due to the presence of a magnetic field. While conventional mr effects are rather small in most semiconductors. Germanium is a typical electronic semiconductor with a cubic lattice. Magnetic semiconductors strong magnetooptical effect allows the material to be used in optical modulators. Basic semiconductor material science and solid state physics. In the second part of the experiment you will study a semiconductor germanium crystal where the leads have already been attached. Earlier researches show that nonmagnetic semiconductormetal hybrid structures exhibit a very large magnetoresistance effect, the socalled extraordinary magnetoresistance effect. Koopmans department of applied physics, center for nanomaterials, and cobra research institute, eindhoven university of technology.
Four probe arrangement, sample, magnetoresistance setup. Magnetoresistance article about magnetoresistance by the. Specifically, the ratio of current, flowing through the highly conducting metal and. Magnetoresistance in semiconductor metal hybrids for power applications presented by clay nunnally, a candidate for the degree of doctor of philosophy and hereby certify that, in their opinion, it is worthy of acceptance. Extraordinary magnetoresistance effect in semiconductor. Dowell associate professor of electrical and computer engineering. Separating positive and negative magnetoresistance in. Coey physics department, trinity college, dublin 2 ireland. To understand metals and semiconductors, we need a better understanding of the electron orbitals in elements than you might have gotten from your intro. Novel experimental setup to study the magnetoresistance.
Electronics tutorial on semiconductor basics explaining what ntype and ptype materials are along with conductors, insulators and resistivity. The magnetoresistance for temperatures below 19 k has been previously reported for this sample where a negative magnetoresistance of 0. Magnetoresistance in semiconductormetal hybrids for power applications presented by clay nunnally, a candidate for the degree of doctor of philosophy and hereby certify that, in their opinion, it is worthy of acceptance. The pace of semiconductor materials and device development has been staggering, and the impact on human society monumental. Magnetoresistance measurements also yield information about current carrier mobilities. Gatetunable large magnetoresistance in an allsemiconductor spintransistorlike device m.
The effect of electric field on the semiconductor surface. Semiconductor devices are nowadays commonplace in every household. Extraordinary magnetoresistance in semiconductormetal. Influence of voltage on magnetization of ferromagnetic. Magneto resistor definition, working, types, and applications. Figure 110 the energy band diagram of a semiconductor. Mr sensors operate virtually independent of magnet shifts and drifts due to lifetime, thermal influences or mechanical stress.
Magnetic semiconductors are semiconductor materials that exhibit both ferromagnetism or a similar response and useful semiconductor properties. The phenomenon of transverse magnetoresistance will be observed in an extrinsic semiconductor. Ferromagneticiiiv semiconductor heterostructures and. Electrical resistivity and hall effect part i overview.
Refer to the experimental guide electrical resistivity and hall effect in germanium. Describe how current is produced in a semiconductor. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. The origin of ferromagnetism kaili zhang literature seminar september 18, 2014 a dilute magnetic semiconductor dms is a semiconductor material that has been made ferromagnetic through doping with transition metal cations at low concentrations. Discuss insulators, conductors, and semiconductors and how they differ. Magnetoresistance overview janicenickel computerperipheralslaboratory hpl9560 june, 1995 magnetoresistance, sal, dualstripe, spinvalve, gmr magnetoresistance, the change of a materials resistivity with the application of a magnetic field, is a well known phenomenon. This is the influence of impurities in semiconductors. An intrinsic semiconductor is an undoped material with an element that shares 8 valence electrons electrons in the outermost shell of an atom with its 4 nearest. Magnetoresistance is the tendency of a material often ferromagnetic to change the value of its electrical resistance in an externallyapplied magnetic field. The spinpolarized carriers are injected and collected by single crystal fe elements, for which the. Separating positive and negative magnetoresistance in organic semiconductor devices f.
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