| 1. |
- Alarco, J A, et al.
(författare)
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Early stages of growth of YBa2Cu3O7− high Tc superconducting films on (001) Y-ZrO2 substrates
- 1994
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 75, s. 3202-3204
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Tidskriftsartikel (refereegranskat)abstract
- Theearly stages of growth of high quality YBa2Cu3O7− (YBCO) filmsgrown on (001) Y-ZrO2 (YSZ) substrates by pulsed laser depositionhave been studied using a combination of atomic force microscopyand transmission electron microscopy. A one unit cell thick YBCOlayer and relatively large CuO particles formed in the initialstages. Additional YBCO grew on top of the first layerin the form of one or a few unit cellhigh c-axis oriented islands about 30 nm in diameter. Therounded islands subsequently coalesced into faceted domains. Elongated Y2BaCuO5 particlesnucleated after the first layer of YBCO. A highly texturedBaZrO3 layer formed between the YSZ and the YBCO witha cube-on-cube dominant orientation relationship with respect to the YBCOfilm. Journal of Applied Physics is copyrighted by The American Institute of Physics.
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| 2. |
- Bogdanov, A. L., et al.
(författare)
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Fabrication of arrays of nanometer size test structures for scanning probe microscope tips characterization
- 1994
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Ingår i: Journal of Vacuum Science & Technology B: Microelectronics Processing and Phenomena. - : American Vacuum Society. - 0734-211X. ; 12:6, s. 3681-3684
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Konferensbidrag (refereegranskat)abstract
- A problem in scanning probe microscopy (SPM) is the unknown shape of the probing tip. Generally, the image is a convolution between the shape of the tip and the surface. Information of the shape of the probe may be gained by imaging very sharp tips. Here we present a method for making two-dimensional arrays of very sharp tips. The tip arrays were made of silicon using electron beam lithography with subsequent ion-beam etching. To achieve the best possible resolution, ultrasonic excitation was used during development of the bilayered PMMA resist. Thus, openings in the resist with size nearly equal to the spot size of the writing e-beam have been obtained. A further decrease of the radius of the tips was obtained by the choice of appropriate thickness for the masking NiCr layer. The tips were conical with a height up to 100 nm with a radius of the tip down to 10 nm. The tips were suitable for study of the shape of AFM probe tips, under condition that the tip array samples were rinsed in water prior to the measurement. Without the rinsing procedure, strong sticking forces between the probe and the sample would have eroded both of them. The regularity of the array provided an easy way to calibrate the lateral motion of the scanner
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| 3. |
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| 4. |
- Davidsson, P, et al.
(författare)
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DESIGN AND OPERATION OF A LOW-TEMPERATURE SCANNING TUNNELING MICROSCOPE SUITABLE FOR OPERATION BELOW 1-K
- 1992
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Ingår i: Ultramicroscopy. - 0304-3991 .- 1879-2723. ; 42-44, s. 1470-1475
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Tidskriftsartikel (refereegranskat)abstract
- A scanning tunneling microscope suitable for very low temperatures has been designed, and preliminary testing has been carried out. In order to improve cooling and temperature uniformity the instrument is arranged for operation immersed in the 3He-4He mixture inside the mixing chamber of a small dilution refrigerator. A discussion of the specific problems present in the design of this kind of an instrument is given as well as a description of our design. Special attention is given to the vacuum sealing and vibration-damping solutions required.
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| 5. |
- Davidsson, P, et al.
(författare)
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Vortex mapping on gold covered conventional type II superconductors using the very low temperature tunnelling microscope
- 1994
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 194-196:Part 1, s. 375-376
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Tidskriftsartikel (refereegranskat)abstract
- We have used a dilution refrigerator cooled STM for investigating the vortex state in lead-bismuth alloy 4000Aofilms. The vortices were recognized by the decreasing dynamic conductance near the gap voltage when the instrument was operated in its normal feed back mode. A clean surface suitable for tunneling was maintained by a 75Aolayer of gold deposited on top of the sample film. The temperature was kept at 80 mK and magnetic fields between 0 and 0.2 T were used.
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| 6. |
- Johansson, L G, et al.
(författare)
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Preparation and properties of Tl2Ba2CaCu2O8 thin films
- 1994
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Ingår i: Journal of Superconductivity. - 0896-1107 .- 1572-9605. ; 7:4, s. 767-771
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Tidskriftsartikel (refereegranskat)abstract
- Anex situ process has been developed to produce thin superconducting Tl2Ba2CaCu2O8 films. The properties of films grown on different substrates using different annealing regimes were studied. Critical temperatures of 103–107 K were measured on films prepared in a broad range of annealing temperatures on SrTiO3, LaAlO3, and Y-ZrO2 substrates. A critical current density,J c, of 2×106 A/cm2 at 77 K was measured on LaAlO3. Film morphology was studied by SEM, AFM, and STM.
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| 7. |
- Kubatkin, S E, et al.
(författare)
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Defect switching in a mesoscopic sample induced by a scanning tunnelling microscope
- 1994
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 6, s. L473-L478
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Tidskriftsartikel (refereegranskat)abstract
- A new method is introduced to study electron transport on the mesoscopic scale. A scanning tunnelling microscope (STM) tip is used both to form a point-contact potential probe to a thin film and to affect scattering centres in its vicinity. We detect abrupt changes in the voltage with this probe as a function of both tip position and tip-sample voltage. These changes could be interpreted as due to spatial shifts of scattering centres in the film surface.
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| 8. |
- Kubatkin, S E, et al.
(författare)
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Movement of scattering centers in a point contact induced by a scanning tunneling microscope
- 1994
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 194-196:Part 1, s. 991-992
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Tidskriftsartikel (refereegranskat)abstract
- A new method is introduced to study transport in a mesoscopic sample. The electric field from an STM-tip is used to locally influence a mesoscopic object. We detect abrupt changes in the mesoscopic signal both as a function of the tip position and tip-sample voltage. They could be interpreted as due to spatial shifts or changes in the activity of scattering centers in the sample.
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| 9. |
- Olin, Håkan
(författare)
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Design of a scanning probe microscope
- 1994
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Ingår i: Measurement science and technology. - TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX : IOP Publishing. - 0957-0233 .- 1361-6501. ; 5, s. 976-984
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Tidskriftsartikel (refereegranskat)abstract
- A compact scanning probe microscope for operation in air and liquid is described. The probe techniques implemented are scanning tunnelling microscopy and scanning ion conductance microscopy. The software, electronics, mechanical construction and some representative measurements are presented. The compact and concentric microscope head is built around a commercial piezoelectric inchworm motor. The scanner is a standard piezo tube. An analogue feedback system is used for taking images, while digital control of the probe-sample distance is used for other experiments, such as measurements of current-voltage characteristics. A Macintosh personal computer is used for control and presentation of data. A simple method to make scanning tunnelling microscope tips suitable for electrochemical use is described. The microscope has a high resonance frequency (9.6 kHz), low noise (0.01 nm Hz- 12 / at 10 Hz), low thermal drift (less than 0.1 nm min-1), and high acoustical noise suppression. The current-distance-dependency of the scanning ion conductance microscope was found to be linear.
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| 10. |
- Olin, Håkan, 1957
(författare)
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Scanning Probe Microscopy: Design and Applications
- 1993
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A compact scanning tunneling microscope (STM) and a scanning ion-conductance microscope (SICM) has been constructed. The concentric microscope head was built around a commercial piezoelectric inchworm motor that was used for coarse positioning. The microscope has a high resonance frequency (9.6 kHz), low noise (0.01 nm/*Hz at 10 Hz), low thermal drift and high acoustical noise suppression. The distance dependence of the SICM-probe was found to be linear. A new kind of pipette with a nanometer sized aperture, intended for use in the SICM, was made by microfabrication methods. An STM-head for operation down to milli Kelvin temperatures has also been constructed. To increase the knowledge of the growth mechanisms and to identify possible flux pinning sites, STM topography was performed at room temperature on high quality laser deposited YBCO thin films. The films were grown at 710-760 °C, and the decreasing critical current density with higher deposition temperature could be related to a change in morphology of the surface. Titanium oxide is a successful biomaterial. However, the mechanism for the biocompatibility is not known. One influencing factor can be the topography at the nanometer scale. We performed STM experiments on three electropolished samples, one without further treatment, one was oxidized, and one was exposed to an argon glow discharge and then oxidized. The two first sample surfaces showed a granular structure, with a corrugation between 2 and 10 nm. At a larger scale, the glow discharge treated sample showed a more pronounced corrugation ~100 nm. A new method for studies of the spatial location of scattering centers in a mesoscopic sample has been invoked. A point contact is first formed between two metallic films by punctuating the insulating interlayer with the aid of an STM tip at liquid helium temperature. The influence on scattering centers in the vicinity of the point contact was studied by scanning the STM tip. Sharp switches in the resistance of the point contact were interpreted as due to spatial shifts or changes in the activity of scattering centers by the electric field around the tip.
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