More importantly, because of its relation to the chiral charge pumping between paired weyl nodes, the negative magnetoresistance is also believed to. Pdf negative magnetoresistance and phase slip process in. The magnetoresistance of a granular superconductor in a strong magnetic field destroying the gap in each grain is considered. A free electron gas would have zero magnetoresistance. The templating, ligand control, and oriented attachment methods have been used to synthesize ultrathin nanowires. Magnetoresistance in the normal and superconducting states of the. Koopmans department of applied physics, center for nanomaterials, and cobra research institute, eindhoven university of technology. Bilayer mott system with cationanion supramolecular. Magnetoresistance of granular superconducting metals in a strong. Negative magnetoresistance an overview sciencedirect. The magnetoresistance of a granular superconductor in a strong magnetic field is considered.
A large negative magnetoresistance nmr is anticipated in topological semimetals in parallel magnetic fields, demonstrating the chiral anomaly, a longsought highenergyphysics effect, in solid. Theory of the magnetoresistance of disordered superconducting films. Atomic origin of spinvalve magnetoresistance at the. A large negative magnetoresistance nmr is anticipated in topological semimetals in parallel magnetic fields, demonstrating the chiral anomaly, a longsought highenergyphysics effect, in. This conclusion is supported by the fact that at high temperatures also the magnetoresistance of ge. Classical origin for a negative magnetoresistance and for.
Springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Heath granular conductors1 are solids comprising densely packed nanoparticles, and have electrical properties that are determined by the size, composition and packing of. The magnitude of the effect in materials used in the recording industry has. The wires show superconducting transition at zero magnetic field, but, there exist a finite. Effect of magnetic field on superconductivity of finea wiley online. The observations that a giant negative magnetoresistance occurs only in materials doped with multiply charged impu. Giant negative magnetoresistance in semiconductors doped by.
Pdf negative hopping magnetoresistance and dimensional. Negative magnetoresistance in in,mnas semiconductors. Negative and positive magnetoresistance in bilayer graphene. We argue that the negative magnetoresistance of superconducting nanowires. Large negative magnetoresistance is usually related to magnetism and the exceptions are rare. Negative magnetoresistance of ultranarrow superconducting nanowires in the resistive state article pdf available in physica c superconductivity 4684. 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. As a result, the potential difference is developed between the upper and bottom surface of the ntype semiconductor. 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. The crossover from two dimensions to one dimension in granular electronic materials ke xu,lidongqin and james r.
Negative magnetoresistance slope in josephson arrays arxiv. Separating positive and negative magnetoresistance in. Maksimova et al 2001 epl 53 639 view the article online for updates and enhancements. Calculations are made for an exactly solvable case of a thinfilm superconductor taking into account the ginzburglandau nonlinearity of the. Nsfsupported researchers have demonstrated that graphene. Classical origin for a negative magnetoresistance and for its. These are trans verse magnetoresistance with field perpendicular to both current and layer. The magnetoresistance is characterized by ppms at 2 k with a magnetic field from. 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.
Pdf negative magnetoresistance of granular metals in a. Hall effect hall effect in conductor, ntype semiconductor. Colossal negative magnetoresistance in adatomengineered. 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. Negative magnetoresistance of amorphous semiconductors. The experimental results can be explained in terms of the onset of a hard motthubbard gap. Under these conditions a giant negative magnetoresistance arises.
Separating positive and negative magnetoresistance in organic. The cofabricated reference film has also been measured and the zero field rt for it is shown in the inset of fig. The observations that a giant negative magnetoresistance occurs only in. The field dependence of the negative magnetoresistance can be described by. Negative magnetoresistance slope in the tesla regime was also observed in tungstenbased nanowire and superconducting ultrathin tin networks by cordoba et al.
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. Currently he is professor of physics at uc berkeley, senior scientist at lbnl, and member of the kavli energy nanosciences institute at berkeley. The crossover from two dimensions to one dimension in. Negative magnetoresistance in amorphous indium oxide wires. Negative magnetoresistance in dirac semimetal cd 3 as 2. It is assumed that the tunneling between grains is sufficiently large. At a large magnetic field the behavior changes to h and then to log h for the longitudinal component of the resistivity. 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. Negative magnetoresistance without chiral anomaly in topological insulators xin dai,1 z. Negative to positive crossover of magnetoresistance in. Magnetoresistance is the tendency of a material often ferromagnetic to change the value of its electrical resistance in an externallyapplied magnetic field. The di erence between dirty super conductors and dirty bose liquids.
So the hall voltage produced in the ntype semiconductor is negative. The shape of the currentvoltage characteristics of the film is determined for arbitrary magnetic field. Phase diagram of electron systems near the superconductorinsulator transition v. He joined the physics department faculty at uc berkeley in 1983. Giant negative magnetoresistance in semiconductors doped. Dowell associate professor of electrical and computer engineering. Magnetoresistance of layered conductors sciencedirect. Critical current and negative magnetoresistance of superconducting film with edge barrier to cite this article. It is further found that the magnetoresistance does not follow kohlers law. The salient features of these unique oscillations indicate the presence of. Negative and positive magnetoresistance in bilayer. 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. Resistivity was measured over the temperature range of 5 to 300 k. We observed a much stronger enhancement of super conductivity in the lowtemperature critical current of our nanowires.
Upper critical field, hall effect and magnetoresistance in. 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. Negative magnetoresistance and phase slip process in. In each pair, the two weyl nodes carry opposite chirality, and. The interplay between the barrier and bulk pinning being. Such large magnetoresistance has been rarely found in molecular conductors. H is the resistivity in the presence of a magnetic. Critical current and negative magnetoresistance of. Spivak, longitudinal negative magnetoresistance and magnetotransport phenomena in conventional and topological con ductors phys. Gigantic negative magnetoresistance in the bulk of a.
The importance of surface barrier sb for a wide range of materials including lowtc super conductors 3 in a. Giant magnetoresistance did not get its name by being a small effect. Phase diagram of electron systems near the superconductor. Superconductivity of inn observed in the magnetoresistance at low. The onset of superconductivity is accounted for by nucleation of the superconducting phase shunting the normal current. Pdf negative magnetoresistance of the normal state of. 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. Aug 20, 2016 a free electron gas would have zero magnetoresistance. 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 2007 nobel prize in physics was awarded to albert fert and peter grunberg for the discovery of gmr. For the transverse magnetoresistance with an increasing field, the dependence becomes h and then. Negative magnetoresistance, negative electroresistance, and metallic behavior on the insulating side of the twodimensional superconductor insulator transition in granular pb films article pdf. Though resistance against temperature at different magnetic fields exhibits similar behavior, we find the temperature dependent longitudinal mr changes from positive to negative in this system, accompanied with a sign change of carrier type. Josephson junctions in the granular wires, arising from the dwave pairing symmetry in yba 2 cu 3 o 7.
Magnetoresistance through a ferromagnetsuperconductor. The charge carrier density determined at 100 k is about 9. However, these mechanisms explain the negative magnetoresistance per. We begin to present our findings by showing the variation of r with t, measured at b 0. Figure 3 shows the magnetoresistance measured at 4. Other effects occur in magnetic metals, such as negative magnetoresistance in ferromagnets 2 or anisotropic magnetoresistance amr. 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. T1 negative magnetoresistance in in,mnas semiconductors. 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. In the ntype semiconductor, the electric field is primarily produced due to the negatively charged free electrons. Separating positive and negative magnetoresistance in organic semiconductor devices f. Pdf recent experimental studies of magnetoresistance in disordered.
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. Negative magnetoresistance due to conductivity fluctuations in films of the topological semimetal cd3as2. In a weakly localized regime of superconducting states finedispersed systems exhibit a negative magnetoresistance. Tunnel magnetoresistance effect and its applications. 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. Pdf negative magnetoresistance of the normal state of the. Periodic negative magnetoresistance in granular yba2cu3 7. The term giant magnetoresistance gmr has come to be associated with certain thin metallic multi. Attaching other chemical species onto the graphene plane offers an effective route to alter and engineer the properties of graphene. The resulting negative magnetoresistance exhibits various types of dependences. Negative magnetoresistance due to conductivity fluctuations. A large magnetoresistance effect in pn junction devices.
Negative magnetoresistance slope in superconducting. May 25, 2017 large negative magnetoresistance is usually related to magnetism and the exceptions are rare. We study magnetotransport properties of several amorphous indium oxide nanowires of different widths. Negative magnetoresistance in dirac semimetal cd3as2. Negative magnetoresistance and nonlinear conduction in ti0. Enhancement of superconductivity by a parallel magnetic field in two. 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. Superconductorinsulator quantum phase transition rutgers physics.
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