Pdf giant negative magnetoresistance in semiconductors doped. 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. Four probe arrangement, sample, magnetoresistance setup. Negative longitudinal magnetoresistance in gaas quantum well. We discuss our results in the framework of known magnetoresistance. Spie 7034, physical chemistry of interfaces and nanomaterials vii, 70340q 21 august 2008. There are a variety of effects that can be called magnetoresistance. Giant negative magnetoresistance of spin polarons in magnetic. Negative and nonlinear magnetoresistance effect in silicon. Pdf giant negative magnetoresistance in semiconductors. At the liquid helium temperature and under application of magnetic fields up to 9.
Pdf negative magnetoresistance of heavily doped silicon. In order to consider only the negative part of the mr figure 2, the present paper is devoted to a tentative. The magnitude of the effect in materials used in the recording industry has. Magnetotransport attracts a lot of attention not only from an academic viewpoint, but also because of its potential spintronics applications. Gigantic negative magnetoresistance in a disordered topological insulator. 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. They have a logarithmic dependence of specific resistance on temperature and negative magnetoresistance. The films have shown room temperature ferromagnetism and ptype conductivity. 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. Articles tuning magnetoresistance between positive and. Negative magnetoresistance of amorphous semiconductors. Intrinsic magnetoresistance in threedimensional dirac. In practice, the polarity of v h determines the sign of the charge carriers. Negative magnetoresistance in dirac semimetal cd 3 as 2.
Giant gatecontrolled proximity magnetoresistance in semiconductor based ferromagnetic nonmagnetic bilayers 25. Lotnikow 3246, 02668 warsaw, poland 2institute of materials science problems, ukrainian academy of sciences, 5 wilde street, 274001. Negative magnetoresistance in organic ionic semiconductor. Aug 20, 2006 experimental results are reported on highfield positive and negative magnetoresistance in semiconducting materials in which variablerange hopping occurs at low temperatures. One of the striking effects is the low temperature giant negative magnetoresistance observed. Anomalous positive or negative magnetoresistance at low temperatures has been observed in germanium, insb, gray tin, inas, gaas, and c. We point out that transport theory in the quantum regime predict the occurence of a negative magnetoresistance.
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. The latter is often considered as evidence of fermions having a defined chirality. The relationships between electrical parameters of samples with gmr and hall configurations are derived. Giant gatecontrolled proximity magnetoresistance in. Gigantic negative magnetoresistance in the bulk of a. Request pdf separating positive and negative magnetoresistance in organic semiconductor devices we study the transition between positive and negative organic magnetoresistance omar in tris. Classical mechanisms, due to disorder or nonuniform current injection, can however, also produce negative longitudinal magnetoresistance. Magnetoresistance is the tendency of a material preferably ferromagnetic to change the value of its electrical resistance in an externallyapplied magnetic field. Negative longitudinal magnetoresistance in gallium.
In the case of positive magnetoresistance, both the mott t. It is found that the transition from the metallic to the lowtemperature insulator phase occurs at an impurity concentration n mn. Negative magnetoresistance in dirac semimetal cd3as2. 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. Resistivity was measured over the temperature range of 5 to 300 k. Negative magnetoresistance due to conductivity fluctuations. Negative to positive crossover of magnetoresistance in. More generally, somewhat complicated magnetoresistances both positive and negative 2,8 have led to theories for the formation of magnetic polarons 1,3,5. A free electron gas would have zero magnetoresistance. Semiconductors have negative temperature coefficient of resistance, i.
Ttfcoonh 3 ph is a recently synthesized openshell ionic semiconductor, the electronic state of which differs from that of typical organic closedshell semiconductors. Negative magnetoresistance in in,mnas semiconductors. Classical origin for a negative magnetoresistance and for its. T1 negative magnetoresistance in in,mnas semiconductors. Crossover of positive to negative magnetoresistance has been observed with the variation of na doping concentrations. The magnetoresistance mr effect of a material is the change in electrical resistance in response to an external magnetic field.
The transition from negative to positive magnetoresistance mr is found to be. Ferromagnetism and crossover of positive magnetoresistance. The resistivity of the doped samples follows the behavior expected of spin magnetic polarons at low temperature. Cdse semiconductor, negative magnetoresistance, low temperature, magnetic field, zeeman effect, localized magnetic moments. Separating positive and negative magnetoresistance in organic. Geometrical magnetoresistance effect in semiconductors with. Negative magnetoresistance due to weak localization and. Introduction molecularelectronics, encompassing theuseof smallmolecules or polymers for use as conductors and semiconductors, has. Kawaji department of physics, gakushuin university, mejiro, toshimaku, tokyo 171, japan received 8 august 1985. Magnetotransport properties were examined using a singlecrystal sample, and found to exhibit small negative magnetoresistance.
Anomalous magnetoresistance in semiconductors jetp. As the spins of so states are locked by the antiferromagnetic interaction, the so to so and do to uo processes do not get suppressed by a magnetic field and we expect that only the negative contribution appears in the magnetoresistance at very low h. Slynko2 1institute of physics, polish academy of sciences, al. Gigantic negative magnetoresistance in a disordered topological. The experimental magnetoresistance mr are plotted as a function of magnetic field in. The magnetoresistance as a function of applied field was described by the khoslafischer model for spin scattering of carriers in an impurity band.
We have extended previous calculations to the case where more than one landau level is populated, taking into account the density of states. Reviews of topical problems related content lanthanum. Negative magnetoresistance in semiconductors in the hopping conduction region. 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. Hemine negative magnetoresistance due to weak localization and electronelectron interactions effects in metallic ntype inp semiconductor at very low temperatures with magnetic field, proc. It is positive if the charge carriers are positive, and negative if the charge carriers are negative.
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. Tuning magnetoresistance between positive and negative. Allowance for the interaction between the electrons also gives rise to an anomalous magnetoresistance whose. Giant negative magnetoresistance in semiconductors doped. Intrinsic magnetoresistance in threedimensional dirac materials. A platform is also provided for placing the sample and mounting the four probes on it. Theory of transport phenomena in degenerate ferromagnetic semiconductors 795. Negative magnetoresistance in tellurium springerlink. The field dependence of the low temperature magnetoresistance was measured. Negative magnetoresistance in transverse and longitudinal. 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. A large negative magnetoresistance nmr is anticipated in topological semimetals in parallel magnetic fields, demonstrating the chiral anomaly, a longsought highenergyphysics effect, in. We are going to treat the magnetoresistance of metals in a quite general and simple manner.
The resistivity decreased with increasing temperature from 90 to 0. Pdf giant negative magnetoresistance in a nonmagnetic. Negative magnetoresistance in the nearest neighbor hopping. 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. Tuning magnetoresistance between positive and negative values. Figure 1a shows the positive and negative magnetoresistance with maximal values of 0. Classical origin for a negative magnetoresistance and for. Separating positive and negative magnetoresistance in. 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. Weak localization and negative magnetoresistance in. Separating positive and negative magnetoresistance in organic semiconductor devices f. Giant unidirectional magnetoresistance in topological. Experiments on ntype gaas are semiquantitatively explained. Pdf separating positive and negative magnetoresistance in.
Conference series negative magnetoresistance in transverse and longitudinal magnetic fields in bi nanowires to cite this article. May 25, 2017 large negative magnetoresistance is usually related to magnetism and the exceptions are rare. B, condensed matter 6320 november 2000 with 35 reads. 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.
Large negative magnetoresistance is usually related to magnetism and the exceptions are rare. Studying an influence of magnetic field on characteristics of such the diodes at 4. Related content low temperature magnetoresistance measurements on bismuth nanowire arrays. Kamimura et al magnetoresistance in andersonlocalized systems temperatures. 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. Giant negative magnetoresistance in niquinoline8selenoate2. Negative magnetoresistance an overview sciencedirect. This anomalous anisotropy of the magnetoresistance is found to be due to the spatial nonuniform distribution of the relaxation time. Large, tunable magnetoresistance in nonmagnetic iiiv. Positive and negative magnetoresistance in the variablerange. Magnetoresistance, the modulation of resistance by magnetic fields, has been adopted and continues to evolve in many device applications including harddisk, memory, and sensors. Both negative magnetoresistance and nonlinear magnetoresisitance were observed in silicon strip nuclear radiation detector in room temperature if we applied. Recently, negative longitudinal and positive inplane transverse magnetoresistance have been observed in most topological diracweyl semimetals, and some other topological materials.
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. Magnetoresistance is the tendency of a material often ferromagnetic to change the value of its electrical resistance in an externallyapplied magnetic field. It shows negative magnetoresistance below the magnetic ordering temperature. Resistivity and magnetoresistance of lanthanum manganites 790 5. 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.
A negative mr is observed below 10 k with an unusual magnitude of about 10% at the lowest temperatures. Koopmans department of applied physics, center for nanomaterials, and cobra research institute, eindhoven university of technology. Negative and anisotropic magnetoresistance in phosphorus. For electron tunneling in a homogeneous material under a nonrandom potential, introduction of a magnetic eld leads usually to a positive magnetoresistance 9. Negative magnetoresistance has been observed in semiconductors, at low temperatures. 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. Na doped zno films were fabricated via a hydrothermal process. Here we present a quantum theory of intrinsic magnetoresistance for threedimensional dirac fermions at a.
Negative magnetoresistance and anomalous hall effect in gemntesnmnte spinglasslike system l. Giant negative magnetoresistance in semiconductors doped by. Negative magnetoresistance of heavily doped silicon pn. Dec 21, 2007 separating positive and negative magnetoresistance in organic semiconductor devices. The positive mr is due to pp exchange interaction induced zeeman splitting to suppress the hopping path of holes. Investigation of negative magnetoresistance nmr of semiconductors doped with nonmagnetic impurities has already a halfcentury history. 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. Negative magnetoresistance and anomalous hall effect in. Magnetoresistance and new related phenomena have been observed in organic semiconductors. A negative magnetoresistance was observed below 17k with a hysteresis in the magnetoresistance observed at 5k.
Theory of negative magnetoresistance proposed recently by the author is presented in details and is applied to heavily doped semiconductors. Negative magnetoresistance behaviour and variable range. Magnetoresistance describes the effect of magnetic fields on electrical resistivity. Epitaxial crdoped ti2o3 films show giant negative magnetoresistance up to 365% at 2 k. In some of these, negative magnetoresistance mr as large as 6 orders of magnitude was observed 6,7. This compound is a semiconductor according to the temperaturedependent resistivity measurements with a roomtemperature resistivity of 0. Ferromagnetism and crossover of positive magnetoresistance to. Kinetic theory of negative magnetoresistance as an. Pdf a giant negative magnetoresistance has been observed in bulk germanium doped with multiply charged deep impurities. Low magnetic field geometrical magnetoresistance effect gmr in semiconductors with mixed conductivity is analyzed. Magnetoresistance in nonmagnetic semiconductors has recently raised much attention and shows great potential due to its large magnitude that is comparable or even larger than magnetic materials. We observe large negative or positive magnetoresistance up to 10% at 300 k and 10 mt depending on material and device operating conditions. Resistivity was measured over the temperature range of 5 to 300k.
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