Negative to positive crossover of magnetoresistance in. The magnetoresistance mr effect of a material is the change in electrical resistance in response to an external magnetic field. Negative and anisotropic magnetoresistance in phosphorus. The latter is often considered as evidence of fermions having a defined chirality. Intrinsic magnetoresistance in threedimensional dirac materials. Transitional metal ditelluride wte2 has been extensively studied owing to its intriguing physical properties like nonsaturating positive magnetoresistance and being possibly a typeii weyl semimetal. Both negative magnetoresistance and nonlinear magnetoresisitance were observed in silicon strip nuclear radiation detector in room temperature if we applied. Magnetoresistance is the tendency of a material often ferromagnetic to change the value of its electrical resistance in an externallyapplied magnetic field. May 25, 2017 large negative magnetoresistance is usually related to magnetism and the exceptions are rare. Recently, negative longitudinal and positive inplane transverse magnetoresistance have been observed in most topological diracweyl semimetals, and some other topological materials. Negative magnetoresistance is observed in specific materials with ferromagnetic components, for example, feni based permalloys, magnetic transition metal oxides, and iiiv semiconductors with magnetic impurity, the socalled. In order to consider only the negative part of the mr figure 2, the present paper is devoted to a tentative. In practice, the polarity of v h determines the sign of the charge carriers. Ttfcoonh 3 ph is a recently synthesized openshell ionic semiconductor, the electronic state of which differs from that of typical organic closedshell semiconductors.
Classical origin for a negative magnetoresistance and for its. A platform is also provided for placing the sample and mounting the four probes on it. Negative magnetoresistance in tellurium springerlink. Ferromagnetism and crossover of positive magnetoresistance. Tuning magnetoresistance between positive and negative values. This anomalous anisotropy of the magnetoresistance is found to be due to the spatial nonuniform distribution of the relaxation time. Ferromagnetism and crossover of positive magnetoresistance to. Articles tuning magnetoresistance between positive and.
The resistivity of the doped samples follows the behavior expected of spin magnetic polarons at low temperature. The magnetoresistance as a function of applied field was described by the khoslafischer model for spin scattering of carriers in an impurity band. Hemine negative magnetoresistance due to weak localization and electronelectron interactions effects in metallic ntype inp semiconductor at very low temperatures with magnetic field, proc. Lotnikow 3246, 02668 warsaw, poland 2institute of materials science problems, ukrainian academy of sciences, 5 wilde street, 274001. It shows negative magnetoresistance below the magnetic ordering temperature. Separating positive and negative magnetoresistance in organic semiconductor devices f. Pdf giant negative magnetoresistance in a nonmagnetic. Pdf giant negative magnetoresistance in semiconductors. The transition from negative to positive magnetoresistance mr is found to be. Negative magnetoresistance in dirac semimetal cd3as2. Conference series negative magnetoresistance in transverse and longitudinal magnetic fields in bi nanowires to cite this article.
Negative magnetoresistance due to weak localization and. Geometrical magnetoresistance effect in semiconductors with. Negative magnetoresistance of heavily doped silicon pn. Spie 7034, physical chemistry of interfaces and nanomaterials vii, 70340q 21 august 2008. The experimental magnetoresistance mr are plotted as a function of magnetic field in. Intrinsic magnetoresistance in threedimensional dirac. Tuning magnetoresistance between positive and negative. Koopmans department of applied physics, center for nanomaterials, and cobra research institute, eindhoven university of technology. Pdf separating positive and negative magnetoresistance in. Classical mechanisms, due to disorder or nonuniform current injection, can however, also produce negative longitudinal magnetoresistance. Crossover of positive to negative magnetoresistance has been observed with the variation of na doping concentrations. It is positive if the charge carriers are positive, and negative if the charge carriers are negative. There are a variety of effects that can be called magnetoresistance.
We are going to treat the magnetoresistance of metals in a quite general and simple manner. Slynko2 1institute of physics, polish academy of sciences, al. Separating positive and negative magnetoresistance in. Materials with large mr are a longstanding goal for research and still at the forefront of contemporary science because of their applications in sensors, memories, and spintronic devices and the fundamental physics of complex interactions. This compound is a semiconductor according to the temperaturedependent resistivity measurements with a roomtemperature resistivity of 0. Negative magnetoresistance has been observed in semiconductors, at low temperatures. Giant gatecontrolled proximity magnetoresistance in semiconductor based ferromagnetic nonmagnetic bilayers 25. Magnetoresistance and new related phenomena have been observed in organic semiconductors. Studying an influence of magnetic field on characteristics of such the diodes at 4. Large, tunable magnetoresistance in nonmagnetic iiiv. Gigantic negative magnetoresistance in the bulk of a. Theory of transport phenomena in degenerate ferromagnetic semiconductors 795. The magnitude of the effect in materials used in the recording industry has. In the case of positive magnetoresistance, both the mott t.
Kawaji department of physics, gakushuin university, mejiro, toshimaku, tokyo 171, japan received 8 august 1985. Figure 1a shows the positive and negative magnetoresistance with maximal values of 0. For the case of a positive magnetoresistance the junction conductance will decrease with increasing magnetic field, whereas for a negative magnetoresistance it will increase with field. Anomalous positive or negative magnetoresistance at low temperatures has been observed in germanium, insb, gray tin, inas, gaas, and c.
Experiments on ntype gaas are semiquantitatively explained. Negative magnetoresistance in semiconductors in the hopping conduction region. While surging research activities were devoted to the understanding of its bulk properties, it remains a substantial challenge to explore the pristine physics in atomically thin wte2. It is found that the transition from the metallic to the lowtemperature insulator phase occurs at an impurity concentration n mn. 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. Here we present a quantum theory of intrinsic magnetoresistance for threedimensional dirac fermions at a. Pdf giant negative magnetoresistance in semiconductors doped. Giant negative magnetoresistance in semiconductors doped by. Epitaxial crdoped ti2o3 films show giant negative magnetoresistance up to 365% at 2 k. The field dependence of the low temperature magnetoresistance was measured. Gigantic negative magnetoresistance in a disordered topological insulator. Anomalous magnetoresistance in semiconductors jetp.
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. Allowance for the interaction between the electrons also gives rise to an anomalous magnetoresistance whose. Magnetoresistance describes the effect of magnetic fields on electrical resistivity. Classical origin for a negative magnetoresistance and for.
Gigantic negative magnetoresistance in a disordered topological. Negative magnetoresistance due to conductivity fluctuations. Magnetoresistance, the modulation of resistance by magnetic fields, has been adopted and continues to evolve in many device applications including harddisk, memory, and sensors. We have extended previous calculations to the case where more than one landau level is populated, taking into account the density of states. Related content low temperature magnetoresistance measurements on bismuth nanowire arrays.
Giant negative magnetoresistance in semiconductors doped. Request pdf separating positive and negative magnetoresistance in organic semiconductor devices we study the transition between positive and negative organic magnetoresistance omar in tris. The positive mr is due to pp exchange interaction induced zeeman splitting to suppress the hopping path of holes. The resistivity decreased with increasing temperature from 90 to 0. Introduction molecularelectronics, encompassing theuseof smallmolecules or polymers for use as conductors and semiconductors, has. T1 negative magnetoresistance in in,mnas semiconductors. Negative magnetoresistance has attracted much interest in the last decades due to the large variety of physical phenomena causing a drop of the resistance of semiconductors in an external magnetic. Pdf a giant negative magnetoresistance has been observed in bulk germanium doped with multiply charged deep impurities.
Theory of negative magnetoresistance proposed recently by the author is presented in details and is applied to heavily doped semiconductors. Negative magnetoresistance in in,mnas semiconductors. Negative magnetoresistance an overview sciencedirect. We discuss our results in the framework of known magnetoresistance. Negative magnetoresistance and anomalous hall effect in. Giant gatecontrolled proximity magnetoresistance in. For electron tunneling in a homogeneous material under a nonrandom potential, introduction of a magnetic eld leads usually to a positive magnetoresistance 9. Resistivity was measured over the temperature range of 5 to 300k. Magnetotransport properties were examined using a singlecrystal sample, and found to exhibit small negative magnetoresistance. It is observed at low temperatures in a large number of semiconductor materials at both sides of metalinsulator transition and realized in semiconductors of both n and ptype. Investigation of negative magnetoresistance nmr of semiconductors doped with nonmagnetic impurities has already a halfcentury history. Resistivity was measured over the temperature range of 5 to 300 k. Negative magnetoresistance in organic ionic semiconductor.
A large negative magnetoresistance nmr is anticipated in topological semimetals in parallel magnetic fields, demonstrating the chiral anomaly, a longsought highenergyphysics effect, in. Giant negative magnetoresistance of spin polarons in magnetic. Cdse semiconductor, negative magnetoresistance, low temperature, magnetic field, zeeman effect, localized magnetic moments. One of the striking effects is the low temperature giant negative magnetoresistance observed. B, condensed matter 6320 november 2000 with 35 reads. Request pdf kinetic theory of negative magnetoresistance as an alternative to weak localization in semiconductors a timeindependent solution to the kinetic equation for the oneelectron. Dec 21, 2007 separating positive and negative magnetoresistance in organic semiconductor devices. Low magnetic field geometrical magnetoresistance effect gmr in semiconductors with mixed conductivity is analyzed. We observe large negative or positive magnetoresistance up to 10% at 300 k and 10 mt depending on material and device operating conditions. 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. Negative magnetoresistance and anomalous hall effect in gemntesnmnte spinglasslike system l. Separating positive and negative magnetoresistance in organic. They have a logarithmic dependence of specific resistance on temperature and negative magnetoresistance.
To explain the origin of the magnetoresistance, a twoband model for conduction in a magnetic semiconductor diode was developed based on the mott model applied. Na doped zno films were fabricated via a hydrothermal process. Aug 20, 2006 experimental results are reported on highfield positive and negative magnetoresistance in semiconducting materials in which variablerange hopping occurs at low temperatures. For heavy phosphorus implantations, the negative magnetoresistance is observed at 77 k and the angular dependences of the magnetoresistance are similar to those of nchannel mosfet. Negative longitudinal magnetoresistance in gaas quantum well. Magnetotransport attracts a lot of attention not only from an academic viewpoint, but also because of its potential spintronics applications. Semiconductors have negative temperature coefficient of resistance, i. Positive and negative magnetoresistance in the variablerange.
Giant unidirectional magnetoresistance in topological. Giant magnetoresistance is at the core of hard disks and onchip sensors, and was the target of the 2007 nobel prize in physics awarded to albert fert and peter grunberg. More generally, somewhat complicated magnetoresistances both positive and negative 2,8 have led to theories for the formation of magnetic polarons 1,3,5. Negative longitudinal magnetoresistance in gallium. Magnetoresistance is the tendency of a material preferably ferromagnetic to change the value of its electrical resistance in an externallyapplied magnetic field. Negative magnetoresistance in dirac semimetal cd 3 as 2.
Kamimura et al magnetoresistance in andersonlocalized systems temperatures. A negative mr is observed below 10 k with an unusual magnitude of about 10% at the lowest temperatures. Giant negative magnetoresistance in niquinoline8selenoate2. Negative and nonlinear magnetoresistance effect in silicon.
Reviews of topical problems related content lanthanum. 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. Negative magnetoresistance in a magnetic semiconducting. Negative anomalous magnetoresistance nam has preciable even in the region of classically weak fields, been experimentally observed in a broad class of where semiconductors over a period of more than twenty o.
Resistivity and magnetoresistance of lanthanum manganites 790 5. Large negative magnetoresistance is usually related to magnetism and the exceptions are rare. The films have shown room temperature ferromagnetism and ptype conductivity. Four probe arrangement, sample, magnetoresistance setup. In some of these, negative magnetoresistance mr as large as 6 orders of magnitude was observed 6,7. Negative magnetoresistance in the nearest neighbor hopping. At the liquid helium temperature and under application of magnetic fields up to 9.
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