The 2007 nobel prize in physics was awarded to albert fert and peter grunberg for the discovery of gmr. A large negative magnetoresistance nmr is anticipated in topological semimetals in parallel magnetic fields, demonstrating the chiral anomaly, a longsought highenergyphysics effect, in. Pdf negative magnetoresistance and phase slip process in. So the hall voltage produced in the ntype semiconductor is negative. Negative magnetoresistance due to conductivity fluctuations. Classical origin for a negative magnetoresistance and for its. Giant magnetoresistance did not get its name by being a small effect.
Josephson junctions in the granular wires, arising from the dwave pairing symmetry in yba 2 cu 3 o 7. We argue that the negative magnetoresistance of superconducting nanowires. Negative and positive magnetoresistance in bilayer. Negative magnetoresistance slope in josephson arrays arxiv. Negative magnetoresistance due to conductivity fluctuations in films of the topological semimetal cd3as2. Phase diagram of electron systems near the superconductor. Separating positive and negative magnetoresistance in organic semiconductor devices f. Resistivity was measured over the temperature range of 5 to 300 k.
Gigantic negative magnetoresistance in the bulk of a. The nonmonotonous field dependence of the differential film resistivity is discovered, which is characterized by a negative magnetoresistance in a lowfield region and by the bardeenstephenlike behaviour in a highfield region. Separating positive and negative magnetoresistance in organic. More importantly, because of its relation to the chiral charge pumping between paired weyl nodes, the negative magnetoresistance is also believed to. The charge carrier density determined at 100 k is about 9. Magnetoresistance in the normal and superconducting states of the. Magnetoresistance through a ferromagnetsuperconductor. In each pair, the two weyl nodes carry opposite chirality, and. Koopmans department of applied physics, center for nanomaterials, and cobra research institute, eindhoven university of technology. Giant negative magnetoresistance in semiconductors doped by. The shape of the currentvoltage characteristics of the film is determined for arbitrary magnetic field. Superconductivity of inn observed in the magnetoresistance at low.
Negative magnetoresistance and nonlinear conduction in ti0. Negative magnetoresistance in amorphous indium oxide wires. A large negative magnetoresistance nmr is anticipated in topological semimetals in parallel magnetic fields, demonstrating the chiral anomaly, a longsought highenergyphysics effect, in solid. Pdf negative hopping magnetoresistance and dimensional.
Pdf recent experimental studies of magnetoresistance in disordered. The term giant magnetoresistance gmr has come to be associated with certain thin metallic multi. Springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Searching for the signature of the adlerbelljackiw chiral anomaly 1,2,3 in threedimensional topological semimetals is one of the focuses in condensed matter physics. We demonstrate that both the positive and negative magnetoresistance can be observed and that the amplitude of the magnetoresistance may be modulated by altering the con. The observations that a giant negative magnetoresistance occurs only in materials doped with multiply charged impu. For the transverse magnetoresistance with an increasing field, the dependence becomes h and then. He joined the physics department faculty at uc berkeley in 1983. Large negative magnetoresistance is usually related to magnetism and the exceptions are rare. Negative magnetoresistance of amorphous semiconductors. Currently he is professor of physics at uc berkeley, senior scientist at lbnl, and member of the kavli energy nanosciences institute at berkeley. Superconductorinsulator quantum phase transition rutgers physics.
In the ntype semiconductor, the electric field is primarily produced due to the negatively charged free electrons. 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. Magnetoresistance of granular superconducting metals in a strong. Magnetoresistance is the tendency of a material often ferromagnetic to change the value of its electrical resistance in an externallyapplied magnetic field. Negative magnetoresistance, localization, low thermal conductivity, ferromagnetism, and quantum size effects are other properties that are of great importance for a variety of applications. Phase diagram of electron systems near the superconductorinsulator transition v. Hall effect hall effect in conductor, ntype semiconductor. Calculations are made for an exactly solvable case of a thinfilm superconductor taking into account the ginzburglandau nonlinearity of the. Giant negative magnetoresistance in semiconductors doped. Negative magnetoresistance slope in the tesla regime was also observed in tungstenbased nanowire and superconducting ultrathin tin networks by cordoba et al. Separating positive and negative magnetoresistance in. We begin to present our findings by showing the variation of r with t, measured at b 0.
We observed a much stronger enhancement of super conductivity in the lowtemperature critical current of our nanowires. 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. A large negative magnetoresistance nmr is anticipated in topological semimetals in parallel magnetic fields, demonstrating the chiral anomaly, a longsought highenergyphysics effect, in solidstate systems. Spivak, longitudinal negative magnetoresistance and magnetotransport phenomena in conventional and topological con ductors phys. The fielddependent critical current i c h and currentvoltage characteristics are found within a generalized criticalstate model that accounts for both surface barrier and bulk pinning as major irreversibility mechanisms in typeii superconductors.
A large magnetoresistance effect in pn junction devices. Aug 20, 2016 a free electron gas would have zero magnetoresistance. It is further found that the magnetoresistance does not follow kohlers law. Tem sample preparation thin foils for stem observations were prepared by a conventional method that includes mechanical polishing of the sample back and then ionbeam milling. The cofabricated reference film has also been measured and the zero field rt for it is shown in the inset of fig. The magnetoresistance of a granular superconductor in a strong magnetic field destroying the gap in each grain is considered. Negative magnetoresistance in in,mnas semiconductors. The wires show superconducting transition at zero magnetic field, but, there exist a finite. Effects of weak localization and charge inhomogeneity yungfu chenn, myungho bae, cesar chialvo, travis dirks, alexey bezryadin, nadya mason department of physics and materials research laboratory, university of illinois at urbanachampaign, urbana, il 618012902, usa. Under these conditions a giant negative magnetoresistance arises. Heath granular conductors1 are solids comprising densely packed nanoparticles, and have electrical properties that are determined by the size, composition and packing of. A free electron gas would have zero magnetoresistance. This conclusion is supported by the fact that at high temperatures also the magnetoresistance of ge.
The salient features of these unique oscillations indicate the presence of. Critical current and negative magnetoresistance of. Attaching other chemical species onto the graphene plane offers an effective route to alter and engineer the properties of graphene. Heath granular conductors1 are solids comprising densely packed nanoparticles, and have electrical properties that are determined by the size, composition and packing of the composite nanoparticles. May 25, 2017 large negative magnetoresistance is usually related to magnetism and the exceptions are rare. Atomic origin of spinvalve magnetoresistance at the. Theory of the magnetoresistance of disordered superconducting films. The field dependence of the negative magnetoresistance can be described by.
The resulting negative magnetoresistance exhibits various types of dependences. Critical current and negative magnetoresistance of superconducting film with edge barrier to cite this article. Negative magnetoresistance slope in superconducting. Related content increase of the critical current at the liquidhelium lambda point in superconducting perforated multilayers. The importance of surface barrier sb for a wide range of materials including lowtc super conductors 3 in a. Negative and positive magnetoresistance in bilayer graphene.
Negative magnetoresistance, negative electroresistance, and metallic behavior on the insulating side of the twodimensional superconductor insulator transition in granular pb films article pdf. Bilayer mott system with cationanion supramolecular. Enhancement of superconductivity by a parallel magnetic field in two. Pdf negative magnetoresistance of the normal state of the. Upper critical field, hall effect and magnetoresistance in. Maksimova et al 2001 epl 53 639 view the article online for updates and enhancements. Pdf negative magnetoresistance of granular metals in a. Figure 3 shows the magnetoresistance measured at 4.
Giant magnetoresistance gmr is a quantum mechanical magnetoresistance effect observed in multilayers composed of alternating ferromagnetic and nonmagnetic conductive layers. The finding of an extremely large magnetoresistance effect on silicon based pn junction with vertical geometry over a wide range of temperatures and magnetic fields is reported. Other effects occur in magnetic metals, such as negative magnetoresistance in ferromagnets 2 or anisotropic magnetoresistance amr. Pdf negative magnetoresistance of the normal state of. Giant negative magnetoresistance of semiinsulating.
Negative to positive crossover of magnetoresistance in. Observation of the chiralanomalyinduced negative magnetoresistance in 3d weyl semimetal taas xiaochun huang,1 lingxiao zhao,1 yujia long,1 peipei wang,1 dong chen,1 zhanhai yang,1 hui liang,1 mianqi xue,1 hongming weng,1,2 zhong fang,1,2 xi dai,1,2 and genfu chen1,2, 1beijing national laboratory for condensed matter physics, and institute of physics, chinese academy of sciences. In a weakly localized regime of superconducting states finedispersed systems exhibit a negative magnetoresistance. Such large magnetoresistance has been rarely found in molecular conductors. The magnetoresistance of a granular superconductor in a strong magnetic field is considered. Pdf superconductivity in nanoscale systems researchgate. Negative magnetoresistance without chiral anomaly in topological insulators xin dai,1 z. As a result, the potential difference is developed between the upper and bottom surface of the ntype semiconductor. Negative magnetoresistance an overview sciencedirect. Magnetoresistance of layered conductors sciencedirect. Du,2,3,4 and haizhou lu2,4, 1institute for advanced study, tsinghua university, beijing 84, china 2institute for quantum science and engineering and department of physics, south university of science and technology of china, shenzhen 518055, china. The magnetoresistance is characterized by ppms at 2 k with a magnetic field from. Negative magnetoresistance in dirac semimetal cd 3 as 2. It is assumed that the tunneling between grains is sufficiently large.
We are going to treat the magnetoresistance of metals in a quite general and simple manner. The interplay between the barrier and bulk pinning being. However, these mechanisms explain the negative magnetoresistance per. The experimental results can be explained in terms of the onset of a hard motthubbard gap. Graphene, a sheet of carbon atoms arranged in a honeycomb lattice, possesses many excellent properties that are potentially useful in electronic, optical and mechanical applications. Negative magnetoresistance without chiral anomaly in. Effects of weak localization and charge inhomogeneity yungfu chenn, myungho bae, cesar chialvo, travis dirks, alexey bezryadin, nadya mason department of physics and materials research laboratory, university of illinois at urbanachampaign, urbana, il 618012902, usa article info. The templating, ligand control, and oriented attachment methods have been used to synthesize ultrathin nanowires. The onset of superconductivity is accounted for by nucleation of the superconducting phase shunting the normal current. The crossover from two dimensions to one dimension in granular electronic materials ke xu,lidongqin and james r. We study magnetotransport properties of several amorphous indium oxide nanowires of different widths.
Bealmonod and weiner explain the negative magnetoresistance found in very dilute magnetic alloys, in terms of the spinflip scattering of conduction electrons off the impurities. Nsfsupported researchers have demonstrated that graphene. Classical origin for a negative magnetoresistance and for. Negative magnetoresistance and phase slip process in. There are a variety of effects that can be called magnetoresistance. Tunnel magnetoresistance effect and its applications. Dowell associate professor of electrical and computer engineering. Effect of magnetic field on superconductivity of finea wiley online. The topological semimetals have a band structure with the conduction and valence energy bands touching at a finite number of paired weyl nodes 4,5,6 fig. At a large magnetic field the behavior changes to h and then to log h for the longitudinal component of the resistivity. Negative magnetoresistance of ultranarrow superconducting nanowires in the resistive state article pdf available in physica c superconductivity 4684. T1 negative magnetoresistance in in,mnas semiconductors. H is the resistivity in the presence of a magnetic. The magnitude of the effect in materials used in the recording industry has.
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