Extraordinary magnetoresistance: sensing the future

Hewett, Thomas H.; Kusmartsev, F. V.

doi:10.2478/s11534-012-0015-1

Cited by 11 publications

(14 citation statements)

References 22 publications

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“…The extraordinary magnetoresistance (EMR) effect discovered by Solin and coworkers led to widespread interest in this phenomenon for magnetic sensing applications [1][2][3][4] . In the original work 1 , an extremely large magnetoresistance was found with the normalized ratio M R = (R(B) − R 0 ) /R 0 as high as 16,000 5 at B = 5 T, in devices comprised of a four-terminal InSb disk with a central metal shunt.…”

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confidence: 99%

Extraordinary magnetoresistance in encapsulated monolayer graphene devices

Zhou

Watanabe

Henriksen

2020

Applied Physics Letters

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We report a proof-of-concept study of extraordinary magnetoresistance (EMR) in devices of monolayer graphene encapsulated in hexagonal boron nitride, having metallic edge contacts and a central metal shunt. Extremely large EMR values, M R = (R(B) − R 0 )/R 0 ∼ 10 5 , are achieved in part because R 0 approaches or crosses zero as a function of the gate voltage, exceeding that achieved in high mobility bulk semiconductor devices. We highlight the sensitivity, dR/dB, which in two-terminal measurements is the highest yet reported for EMR devices, and in particular exceeds prior results in graphene-based devices by a factor of 20. An asymmetry in the zero-field transport is traced to the presence of pn-junctions at the graphene-metal shunt interface.

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confidence: 99%

Extraordinary magnetoresistance in encapsulated monolayer graphene devices

Zhou

Watanabe

Henriksen

2020

Applied Physics Letters

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“…See Refs. [ 27 , 28 ] for detailed discussions on these issues. Note that here we observe slight negative magnetoresistances, see Figure 3 a.…”

Section: Resultsmentioning

confidence: 99%

Photon Drag Currents and Terahertz Generation in α-Sn/Ge Quantum Wells

Zhang¹,

Luo²,

Liu³

et al. 2022

Nanomaterials

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We have fabricated α-Sn/Ge quantum well heterostructures by sandwiching nano-films of α-Sn between Ge nanolayers. The samples were grown via e-beam deposition and characterized by Raman spectroscopy, atomic force microscopy, temperature dependence of electrical resistivity and THz time-resolved spectroscopy. We have established the presence of α-Sn phase in the polycrystalline layers together with a high electron mobility μ = 2500 ± 100 cm2 V−1 s−1. Here, the temperature behavior of the resistivity in a magnetic field is distinct from the semiconducting films and three-dimensional Dirac semimetals, which is consistent with the presence of linear two-dimensional electronic dispersion arising from the mutually inverted band structure at the α-Sn/Ge interface. As a result, the α-Sn/Ge interfaces of the quantum wells have topologically non-trivial electronic states. From THz time-resolved spectroscopy, we have discovered unusual photocurrent and THz radiation generation. The mechanisms for this process are significantly different from ambipolar diffusion currents that are responsible for THz generation in semiconducting thin films, e.g., Ge. Moreover, the THz generation in α-Sn/Ge quantum wells is almost an order of magnitude greater than that found in Ge. The substantial strength of the THz radiation emission and its polarization dependence may be explained by the photon drag current. The large amplitude of this current is a clear signature of the formation of conducting channels with high electron mobility, which are topologically protected.

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“…When the highest carrier densities are used in the four geometries, we observe the common feature of a very low device resistance that is only weakly dependent on the magnetic field. In this case, the conductivity of the semiconductor is similar to or even exceeds that of the metal, and as the conductivity contrast across the metal/semiconductor interface becomes small, its capability to deflect the current path in magnetic fields vanishes [13]. Hence, the EMR effect is suppressed for all geometries.…”

Section: Carrier Densitymentioning

confidence: 99%

“…Previous studies have explored the role of material properties by varying them with the use of finite element simulations and have found that achieving a high magnetoresistance generally requires a high electron mobility in the semiconductor, high electrical conductivity of the metal, as well as a low contact resistance between the two material regions [10,12,13]. In particular, for the benchmark concentric circular geometry, it was found that increasing the mobility from 500 to 200 000 cm 2 Vs −1 increased the magnetoresistance at 1 T by three orders of magnitude, whereas the magnetoresistance completely vanished for high semiconductor/metal contact resistances [13]. The material requirements sparked an interest in studying the behavior of EMR in various high-mobility materials, including InSb [8,[12][13][14][15][16][17], InAs [18][19][20], GaAs [21][22][23][24] and graphene [25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Universal material trends in extraordinary magnetoresistive devices

Erlandsen,

Désiré Pomar,

Kornblum

et al. 2023

J. Phys. Mater.

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Extraordinary magnetoresistance (EMR) is a geometric magnetoresistance emerging in hybrid systems typically comprising a high-mobility material and a metal. Due to a field-dependent redistribution of electrical currents in these devices, the electrical resistance at room temperature can increase by 10^7% when applying a magnetic field of 5 T. Although EMR holds considerable potential for realizing sensitive, all-electronic magnetometers, this potential is largely unmet. A key challenge is that the performance of EMR devices depends very sensitively on variations in a vast parameter space where changes in the device geometry and material properties produce widely different EMR performances. The challenge of navigating in the large parameter space is further amplified by the poor understanding of the interplay between the device geometry and material properties. By systematically varying the material parameters in four key EMR geometries using diffusive transport simulations, we here elucidate this interplay with the aim of finding universal guidelines for designing EMR devices. Common to all geometries, we find that the sensitivity scales inversely with the carrier density, while the MR reaches saturation at low carrier densities. Increasing the mobility beyond 20,000 cm^2/Vs is required to observe strong EMR effects at 1 T with the optimal magnetoresistance observed for mobilities between 100,000-500,000 cm^2/Vs. An interface resistance below 10^-4 Ohm*cm^2 between the constituent materials in the hybrid devices was also found to be a prerequisite for very high magnetoresistances in all geometries. By further simulating several high-mobility materials at room and cryogenic temperatures, we conclude that encapsulated graphene and InSb are amongst the most promising candidates for EMR devices showing high magnetoresistance exceeding 10^7% below 1 T at room temperature. This study paves the way for understanding how to realize EMR devices with record-high magnetoresistance and high sensitivity for detecting magnetic fields.

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Extraordinary magnetoresistance: sensing the future

Cited by 11 publications

References 22 publications

Extraordinary magnetoresistance in encapsulated monolayer graphene devices

Extraordinary magnetoresistance in encapsulated monolayer graphene devices

Photon Drag Currents and Terahertz Generation in α-Sn/Ge Quantum Wells

Universal material trends in extraordinary magnetoresistive devices

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