Marius grundmann the physics of semiconductors fulvio frisone. The magnetoresistance for temperatures below 19 k has been previously reported for this sample where a negative magnetoresistance of 0. Basic semiconductor material science and solid state physics. Separating positive and negative magnetoresistance in organic semiconductor devices f. You will 1 measure the temperaturedependence of resistivity, 2 determine the energy gap e g, and 3 study the hall effect. Magnetoresistivity can now depend on magnetic field, angle, and.
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. Describe how current is produced in a semiconductor. Specifically, the ratio of current, flowing through the highly conducting metal and. Magnetoresistive angular sensors nxp semiconductors.
Magnetoresistance and hall effect in the ferromagnetic. Paramagnetic semiconductor cd 1x mn x te is promising as a magnetooptical. 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. Magnetooptical devices for optical integrated circuits. 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. Hall coefficient and transverse magnetoresistance of narrow. Dowell associate professor of electrical and computer engineering. Magnetoresistance article about magnetoresistance by the. New kind of magnetoresistance has implications for. If implemented in devices, these materials could provide a new type of control of conduction. Matthew melissa physics 141a spring 20 1 giant magnetoresistance matthew melissa april 4, 20. In the second part of the experiment you will study a semiconductor germanium crystal where the leads have already been attached.
Magnetic semiconductors strong magnetooptical effect allows the material to be used in optical modulators. The phenomenon of transverse magnetoresistance will be observed in an extrinsic semiconductor. 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. 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. 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. Extraordinary magnetoresistance effect in semiconductor. Figure 110 the energy band diagram of a semiconductor.
Magnetoresistance definition of magnetoresistance by. Earlier researches show that nonmagnetic semiconductormetal hybrid structures exhibit a very large magnetoresistance effect, the socalled extraordinary magnetoresistance effect. Semiconductors are good for testing theory because they offer another dimension for measuring resistivity. Magnetoresistance definition is a change in electrical resistance due to the presence of a magnetic field. Magnetoresistance an overview sciencedirect topics.
The element which has these effects is known as the magnetoresistor. This vlmr occurs when the electrons occupy the open fermi surface and their motion. Very large tunneling magnetoresistance in layered magnetic. Important to practical applications is the fact that the geometry of a semiconductor sample can generate very large magnetoresistance, as in the corbino disk.
Novel experimental setup to study the magnetoresistance. Magnetic force revisited you saw in an earlier section that charges moving through a magnetic field experience a magnetic force given by f b qv x b. Hall coefficient and magnetoresistance of semiconductors. Separating positive and negative magnetoresistance in. It is shown that in a weak magnetic field the transport coefficients exhibit non. Magnetoresistance measurements also yield information about current carrier mobilities. Whereas traditional electronics are based on control of charge carriers nor ptype, practical magnetic semiconductors would also allow control of quantum. In the late 1940s the invention of the transistor was the start of a rapid development. Gatetunable large magnetoresistance in an allsemiconductor spintransistorlike device m. The semiconductor materials used in electronic devices are doped under precise conditions to control the concentration and regions of p and ntype dopants. The pace of semiconductor materials and device development has been staggering, and the impact on human society monumental. To understand metals and semiconductors, we need a better understanding of the electron orbitals in elements than you might have gotten from your intro. Magnetoresistance of inmnas magnetic semiconductors. Vertical longitudinal magnetoresistance vlmr caused by the peculiar shape of the fermi surface of a superlattice has been observed in gaasalxga1xas superlattices.
Based on ab initio calculations, we associate the origin of the phenomenon with large anisotropies in the relativistic electronic structure. While conventional mr effects are rather small in most semiconductors. Ferromagneticiiiv semiconductor heterostructures and. 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. Four probe arrangement, sample, magnetoresistance setup. Semiconductor devices are nowadays commonplace in every household. Their faraday rotation can be up to six orders of magnitude higher than that of nonmagnetic semiconductors. Ravindran, phy02e semiconductor physics, 30 january 20. Ferromagnetism and giant magnetoresistance in zincblende. Mr sensors operate virtually independent of magnet shifts and drifts due to lifetime, thermal influences or mechanical stress.
Koopmans department of applied physics, center for nanomaterials, and cobra research institute, eindhoven university of technology. Universal properties of linear magnetoresistance in strongly disordered mnasgaas. In this dissertation, the extraordinary magnetoresistance emr effect in semiconductormetal hybrid structures is studied to improve the performance in sensing applications. Magnetic properties of gamnas nanodot arrays fabricated using porous alumina templates1pg. The dependence of the magnetoresistance on applied magnetic field will be determined and compared to theoretical predictions. 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. 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. The silicon becomes an ntype semiconductor because of the addition of.
The effect of electric field on the semiconductor surface. Issues in colossal magnetoresistance cmr manganese oxides. Magnetic field can also be used to cause the metal to semiconductor transition, a phenomenon also called colossal magnetoresistance. This is the influence of impurities in semiconductors. Extraordinary magnetoresistance in semiconductormetal. Refer to the experimental guide electrical resistivity and hall effect in germanium. But the garnetmade isolators have not been monolithically integrated with semiconductor optoelectronic devices, because these oxide crystals can not be grown on semiconductor substrates.
Magneto resistor is a type of resistor whose resistance changes when an external magnetic field is applied. In a thought experiment in free space, another observer, attached to frame o x,y,z, moves at velocity v c2. There are a variety of effects that can be called magnetoresistance. 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. Magneto resistor definition, working, types, and applications. The spinpolarized carriers are injected and collected by single crystal fe elements, for which the. Today, highly integrated semiconductor detector systems with tens of thousands of.
Magnetism and semiconducting properties are known to coexist in some ferromagnetic. The x is a crossproduct, which means that the magnitude size of the force is found from. In other words, the magnetoresistor is a type of resistor whose resistance varies with the magnetic field. Magnetoresistance effects in hybrid semiconductor devices. Electronics tutorial on semiconductor basics explaining what ntype and ptype materials are along with conductors, insulators and resistivity. Plots of magnetoresistance versus magnetic field at four different temperatures are shown in. Semiconductors with electric and magnetic properties. In other words, the flow of electric current through the magneto resistor changes when an external magnetic field is applied to it. The fifth electron becomes a conduction electron that is donated to the conduction band. Magnetic semiconductors are semiconductor materials that exhibit both ferromagnetism or a similar response and useful semiconductor properties. Magnetoresistance is the tendency of a material often ferromagnetic to change the value of its electrical resistance in an externallyapplied magnetic field. Dowell associate professor of electrical and computer. Magnetoresistance of semiconductormetal hybrid structures. Magnetoresistance effects in hybrid semiconductor devices citation for published version apa.
The transverse magnetoresistance of the inmnas layer was measured in magnetic fields up to 1 t and in the temperature range of 1961 k. Coey physics department, trinity college, dublin 2 ireland. Discuss insulators, conductors, and semiconductors and how they differ. The resistivity, temperature, and magnetic field dependence of the anomalous hall effect in a series of metallic ga1. Giant room temperature magnetoresistance in singlecrystal femgofe magnetic tunnel juctins, nature vol. 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. Magnetoelectronics at edges in semiconductor structures. Anisotropic magnetoresistance in an antiferromagnetic. The magnitude of the effect in materials used in the recording industry has. Influence of voltage on magnetization of ferromagnetic. We are going to treat the magnetoresistance of metals in a quite general and simple manner. Germanium is a typical electronic semiconductor with a cubic lattice. Electrical resistivity and hall effect part i overview. 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.