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Scanning Hall probe microscopy of superconductors and magnetic materials

A. Oral
1996 Journal of Vacuum Science & Technology B Microelectronics Processing and Phenomena  
We describe results from a scanning Hall probe microscope operating in a broad temperature range, 4 -300 K.  ...  A submicron Hall probe manufactured in a GaAs/AlGaAs two-dimensional electron gas is scanned over the sample to measure the surface magnetic fields using conventional scanning tunneling microscopy positioning  ...  The field resolution is improved to ϳ1.1ϫ10 Ϫ3 G/ͱHz at 77.6 K and estimated to be ϳ2ϫ10 Ϫ4 G/ͱHz at 4.2 K.  ... 
doi:10.1116/1.588514 fatcat:z6m5vnjj2vg7ziowux5y4vadya

Real‐time scanning Hall probe microscopy

A. Oral, S. J. Bending, M. Henini
1996 Applied Physics Letters  
A PZT-5H piezotube is used for the scanner with a ϳ10 m scan range at 4.2 K.  ...  The active Hall sensor is patterned about 13 m away from the chip corner which has been coated with a thin layer of gold to serve as a tunneling tip.  ...  Our Hall probes can sustain currents up to 4 A at 300 K and up to 60 A below 77 K, without increasing the noise and typical series resistances are 60, 3, and 1.5 K⍀ are 300, 77, and 4.2 K, respectively  ... 
doi:10.1063/1.117582 fatcat:duwtu745rncmvj5jjfy7pnkmha

Scanning Tunneling Spectroscopy inMgB2

G. Karapetrov, M. Iavarone, W. K. Kwok, G. W. Crabtree, D. G. Hinks
2001 Physical Review Letters  
We present scanning tunneling microscopy measurements of the surface of superconducting MgB2 with a critical temperature of 39K.  ...  The value of the superconducting gap is 5.2 meV at 4.2 K, with no experimentally significant variation across the surface of the sample.  ...  The fitting curve and the experimental points have been normalized to the gap value at 4.2 K ( ∆=5.2 meV) and a T c =35 K.  ... 
doi:10.1103/physrevlett.86.4374 pmid:11328178 fatcat:e5byty3mhjar3dhgy2gquowrqu

Extrinsic and intrinsic magnetoresistance contributions of CrO2 thin films

U. Rüdiger, M. Rabe, K. Samm, B. Özyilmaz, J. Pommer, M. Fraune, G. Güntherodt, St. Senz, D. Hesse
2001 Journal of Applied Physics  
Magnetotransport studies have been performed from 4.2 to 300 K in all field a͒ Author to whom correspondence should be addressed; electronic mail: In magnetic thin films  ...  A clear indicator of the better crystalline quality of CrO 2 films grown on TiO 2 ͑100͒ substrates compared to Al 2 O 3 ͑0001͒ is the residual resistivity ratio ͑RRR͒ defined as R 300 K /R 4.2 K .  ... 
doi:10.1063/1.1362658 fatcat:7mv4ihdeljf4rg3zkp7crunvqe

Study of Penetration of Polar Molecules through Lead Films by Inelastic Electron Tunneling Spectroscopy and Atomic Force Microscopy

Morihide HIGO, Youichi IKEDA, Shunichi KIDOGUCHI, Masaru MITSUSHIO, Toshifumi YOSHIDOME
2010 Journal of the Japan Society of Colour Material  
and atomic force microscopy AFM .  ...  From the analysis of IET spectra of penetrated formic acid, acetic acid, and methanesulfonic acid and the morphology observation of the lead-top electrodes, these organic acids were found to penetrate  ...  Tunneling spectra of water-infused and undoped alumina measured at 4.2 K.  ... 
doi:10.4011/shikizai.83.249 fatcat:pphyazkirfepdlccqtjijuj6hm

Charge Carrier Transport Properties in Single-Walled Carbon Nanotube Fibers

V.K. Ksenevich, D. Seliuta, Z. Martūnas, I. Kašalynas, G. Valušis, J. Galibert, M.E. Kozlov, V.A. Samuilov
2008 Acta Physica Polonica. A  
The R(T ) dependences studied within 4.2-300 K can be well approximated by the Mott law for 3D variable range hopping below T = 80 K and by typical law for fluctuation-induced tunnelling model within the  ...  temperature range 80-300 K.  ...  In order to determine transport mechanisms, the temperature dependences of resistance R(T ) of SWCNT fibers were measured in the range of 4.2-300 K.  ... 
doi:10.12693/aphyspola.113.1039 fatcat:52j3jc6lbfb5thjalne576gjyq

Structural Modulation in LaO0.9F0.1BiSe2 Single Crystals Revealed by Scanning Tunneling Microscopy/Spectroscopy

N Ishida, S Demura, Y Fujisawa, S Ohta, K Miyata, H Sakata
2018 Journal of Physics, Conference Series  
We present scanning tunneling microscopy and spectroscopy measurements on a cleaved surface of the LaO0.9F0.1BiSe2 single crystals.  ...  The period of the supermodulation was about 3 to 5 times the length of the lattice constant. This period is close to that observed in LaO0.5F0.5BiSe2.  ...  STM/STS measurements were performed with laboratory-built STM in the He gas at 4.2 K. The clean surface of LaO0.9F0.1BiSe2 single crystal was prepared by cleavage at 4.2 K in situ.  ... 
doi:10.1088/1742-6596/1054/1/012001 fatcat:6omrzknd3naatkyqqgpcujxufu

Large-scale fabrication of BN tunnel barriers for graphene spintronics

Wangyang Fu, Péter Makk, Romain Maurand, Matthias Bräuninger, Christian Schönenberger
2014 Journal of Applied Physics  
We have fabricated graphene spin-valve devices utilizing scalable materials made from chemical vapor deposition (CVD).  ...  We find that spin injection is still greatly suppressed in devices with a monolayer tunneling barrier due to resistance mismatch. This is, however, not the case for devices with bilayer barriers.  ...  Acknowledgments The authors acknowledge funding from the Swiss National Science Foundation (SNF),  ... 
doi:10.1063/1.4893578 fatcat:b3snkf6frvg4tohkpv3af62hoa

Electrical studies of single‐barrier Hg1−xCdxTe heterostructures

D. H. Chow, J. O. McCaldin, A. R. Bonnefoi, T. C. McGill, I. K. Sou, J. P. Faurie, F. A. Shirland, O. K. Wu
1988 Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films  
This analysis is applied to data from each of three samples, yielding values of the HgTe-CdTe valence-band discontinuity between 290 ± 50 and 390 ± 75 meV at 300 K.  ...  Current-voltage curves are taken at 4.2 K, yielding a novel single-barrier negative differential resistance (NDR) due to electron tunneling.  ...  ACKNOWLEDGMENTS We wish to acknowledgeS. Nieh for providing us with important TEM data, and 0. J. Marsh, T. K. Woodward, and M. B. Johnson for valuable discussions and assistance.  ... 
doi:10.1116/1.575517 fatcat:sdkphuwxzrel7lxwzh65tn6cqq

Temperature Characterization of Unipolar-Doped Electroluminescence in Vertical GaN/AlN Heterostructures

Weidong Zhang, Tyler A. Growden, Paul R. Berger, David F. Storm, David J. Meyer, Elliott R. Brown
2021 Energies  
An electroluminescence (EL) phenomenon in unipolar-doped GaN/AlN/GaN double-barrier heterostructures—without any p-type contacts—was investigated from 4.2 K to 300 K.  ...  In the range of 200–300 K, the extracted peak photon energies agree with the Monemar formula. In the range of 30 to 200 K, the photon energies are consistent with A-exciton emission.  ...  Figure 2b plots the I-V curves at eight different temperatures ranging from 4.2 to 300 K, showing only slight variations.  ... 
doi:10.3390/en14206654 fatcat:5w4dq2s7kfev5hhd4echz3ycpy

Scanning-tunneling microscopy/spectroscopy and break-junction tunneling spectroscopy of FeSe1–xTex

T. Ekino, A. Sugimoto, A. M. Gabovich
2013 Low temperature physics (Woodbury, N.Y., Print)  
The superconducting gap 2Δ ≈ 3.4 ± 0.2 meV at temperature T = 4.2 K was found in the break junction of FeSe 1-x Te x with the critical temperature T c ≈ 10 K.  ...  The corresponding characteristic gap to T c ratio 2Δ/k B T c ≈ 4 ± 0.2 indicates moderate superconducting coupling (k B is the Boltzmann constant). PACS: 74.50.  ...  Fig. 5 . 5 The dI/dV curves of FeSe 0.5 Te 0.5 (a) at 4.2 K from breakjunction tunneling spectroscopy (BJTS).  ... 
doi:10.1063/1.4795173 fatcat:tzk4phi76jeppiuknmehk677ca

A stiff scanning tunneling microscopy head for measurement at low temperatures and in high magnetic fields

S. C. White, U. R. Singh, P. Wahl
2011 Review of Scientific Instruments  
We demonstrate operation of the STM head in topographic imaging and tunneling spectroscopy at temperatures down to below 2 K.  ...  We have developed a measurement head for scanning tunneling microscopy (STM) and specifically for spectroscopic imaging STM which is optimized for high mechanical stiffness and good thermal conductivity  ...  Downloaded to IP: On: Fri, 10 Jan 2014 12:52:50 Figure 6 (a) shows tunneling spectra acquired on NbSe 2 at 4.2 K, 3 K (under temperature control 35 ), and 1.7 K.  ... 
doi:10.1063/1.3663611 pmid:22128985 fatcat:szcpopaoc5cdramliusj2vnb5q

Single electron tunneling and level spectroscopy of isolated C60 molecules

Danny Porath, Oded Millo
1997 Journal of Applied Physics  
The tunneling current-voltage characteristics of isolated molecules, both at room temperature and at 4.2 K, exhibit rich structures, resulting from the interplay between charging effects and the electronic  ...  The interplay between single electron tunneling effects and the discrete molecular levels of C 60 molecules is studied using scanning tunneling microscopy.  ...  FIG. 3 . 3 Tunneling spectroscopic dI/dV traces at 4.2 K ͓͑a͒, ͑b͒, and right inset͔ and at 300 K ͑c͒. The traces were acquired with different STM settings.  ... 
doi:10.1063/1.364275 fatcat:rjtiz63pgjgwtpe5m6wxkecgke

Variable Temperature-Scanning Hall Probe Microscopy With GaN/AlGaN Two-Dimensional Electron Gas (2DEG) Micro Hall Sensors in 4.2–425 K Range Using Novel Quartz Tuning Fork AFM Feedback

R. Akram, M. Dede, A. Oral
2008 IEEE transactions on magnetics  
Simultaneous scans of magnetic and topographic data at various pressures (from atmospheric pressure to high vacuum) from 4. to 425K will be presented for different samples to illustrate the capability  ...  The active area, Hall coefficient, carrier concentration, and series resistance of the Hall sensors were 1 1 m, 10 m/G at 4.2 K, 6.3 10 12 cm 2 and 12 k at room temperature and 7 m/G, 8.9 10 12 cm 2 and  ...  The authors would like to thank M. Demir for his continuous support and for the upkeep of the microscope.  ... 
doi:10.1109/tmag.2008.2001622 fatcat:o334vlxbcrczzgyrosuq2kvdza

High-Current GaSb/InAs(Sb) Nanowire Tunnel Field-Effect Transistors

Anil W. Dey, B. Mattias Borg, Bahram Ganjipour, Martin Ek, Kimberly A. Dick, Erik Lind, Claes Thelander, Lars-Erik Wernersson
2013 IEEE Electron Device Letters  
Devices with scaled gate oxides display transconductances up to gm = 250 mS/mm at VDS = 300 mV, normalized to the nanowire circumference at the axial heterojunction.  ...  The broken band alignment of the GaSb/InAs(Sb) heterostructure is exploited to allow for inter-band tunneling without a barrier, leading to high on-current levels.  ...  (b) Temperature dependent I DS -V GS characteristics and (c) transconductance at V DS = 300 mV from 4.2 K to 242 K, ∆T ≈ 50 K. Anil W. Dey, B. Mattias Borg, Bahram Ganjipour, Martin Ek, Kimberly A.  ... 
doi:10.1109/led.2012.2234078 fatcat:wilibhdvcvchxkc7zsbukilbki
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