Magnetoresistance of amorphous indium oxide films at the region of weak-strong localization crossover

Lee, Y J; Kim, Y S; Shin, Heecheol

doi:10.1088/0953-8984/14/3/316

Cited by 5 publications

(3 citation statements)

References 17 publications

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“…Results of MC measurements on In x O films were reported by Lee et al [26]. Their results differed from ours; they observed positive MC only above 8-10K while the low field MC became negative at lower temperatures.…”

Section: Resultscontrasting

confidence: 75%

Compositional disorder and transport peculiarities in the amorphous indium oxides

Givan

Ovadyahu

2012

Phys. Rev. B

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We present results of the disorder-induced metal-insulator-transition (MIT) in three-dimensional amorphous indium-oxide films. The amorphous version studied here differs from the one reported earlier [Phys. Rev. B 46, 10917 (1992)] in that it has a much lower carrier concentration. As a measure of the static disorder we use the dimensionless parameter kF ℓ. Thermal annealing is employed as the experimental handle to tune the disorder. On the metallic side of the transition, the low temperature transport exhibits weak-localization and electron-electron correlation effects characteristic of disordered electronic systems. These include a fractional power-law conductivity versus temperature behavior anticipated to occur at the critical regime of the transition. The MIT occurs at a kF ℓ ≈0.3 for both versions of the amorphous material. However, in contrast with the results obtained on the electron-rich version of this system, no sign of superconductivity is seen down to ≈0.3K even for the most metallic sample used in the current study. This demonstrates that using kF ℓ as a disorder parameter for the superconductor-insulator-transition (SIT) is an ill defined procedure. A microstructural study of the films, employing high resolution chemical analysis, gives evidence for spatial fluctuations of the stoichiometry. This brings to light that, while the films are amorphous and show excellent uniformity in transport measurements of macroscopic samples, they contain compositional fluctuations that extend over mesoscopic scales. These, in turn, reflect prominent variations of carrier concentrations thus introducing an unusual type of disorder. It is argued that this compositional disorder may be the reason for the apparent violation of the Ioffe-Regel criterion in the two versions of the amorphous indium-oxide. However, more dramatic effects due to this disorder are expected when superconductivity sets in, which are in fact consistent with the prominent transport anomalies observed in the electron-rich version of indium-oxide. The relevance of compositional disorder (or other agents that are effective in spatially modulating the BCS potential) to other systems near their SIT is discussed. PACS numbers: 72.80.Ng 72.15.Rn 68.55.Ln 68.35.Dv Typeset by REVT E X

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Section: Resultscontrasting

confidence: 75%

Compositional disorder and transport peculiarities in the amorphous indium oxides

Givan

Ovadyahu

2012

Phys. Rev. B

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“…One way to prove this is by confirming magnetoresistance in the system. Figure 3(c) shows the room-temperature magnetoresistance curve of an FDTO film deposited at 2 × 10 −6 Torr, demonstrating positive magnetoresistance where resistance increases with increasing magnetic field, a phenomenon that has been reported in several disordered and granular magnetic systems [44][45][46][47][48] . Although the %MR in FDTO is lower than that in Fe 3 O 4 , the existence of magnetoresistance confirmed the coupling between spin and charge carriers in FDTO, and hence consolidating its utility towards magnetoelectric devices.…”

Section: Resultsmentioning

confidence: 55%

Integration of amorphous ferromagnetic oxides with multiferroic materials for room temperature magnetoelectric spintronics

Taz

Prasad

Huang

et al. 2020

Sci Rep

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A room temperature amorphous ferromagnetic oxide semiconductor can substantially reduce the cost and complexity associated with utilizing crystalline materials for spintronic devices. We report a new material (fe 0.66 Dy 0.24 Tb 0.1) 3 o 7-x (FDTO), which shows semiconducting behavior with reasonable electrical conductivity (~500 mOhm-cm), an optical band-gap (2.4 eV), and a large enough magnetic moment (~200 emu/cc), all of which can be tuned by varying the oxygen content during deposition. Magnetoelectric devices were made by integrating ultrathin FDTO with multiferroic BiFeO 3. A strong enhancement in the magnetic coercive field of FDTO grown on BiFeO 3 validated a large exchange coupling between them. Additionally, FDTO served as an excellent top electrode for ferroelectric switching in BiFeO 3 with no sign of degradation after ~10 10 switching cycles. RT magneto-electric coupling was demonstrated by modulating the resistance states of spin-valve structures using electric fields.

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“…͑1͒ and ͑2͒, although derived on the condition of k F l ӷ 1, can be applied in a strongly localized 2D electron gas with k F l = 0.5-2. Lee et al 7 also showed the validity of Eq. ͑2͒ beyond the WL regime.…”

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confidence: 81%

Large negative magnetoresistance and strong localization in highly disordered electrospun pregraphitic carbon nanofiber

Wang

Santiago-Avilés

2006

Applied Physics Letters

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Magnetoresistance of amorphous indium oxide films at the region of weak-strong localization crossover

Cited by 5 publications

References 17 publications

Compositional disorder and transport peculiarities in the amorphous indium oxides

Compositional disorder and transport peculiarities in the amorphous indium oxides

Integration of amorphous ferromagnetic oxides with multiferroic materials for room temperature magnetoelectric spintronics

Large negative magnetoresistance and strong localization in highly disordered electrospun pregraphitic carbon nanofiber

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