A low temperature scanning tunneling microscope for electronic and force spectroscopy

Smit, R. H. M.; Grande, Rafael; Lasanta, B.; Riquelme, J.; Rubio‐Bollinger, Gabino; Agraı̈t, Nicolás

doi:10.1063/1.2804165

Cited by 25 publications

(26 citation statements)

References 18 publications

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“…Typical current noise levels correspond to height changes of the order of the pm. Vibrations should be of the order or below this value [163,167]. The resonant frequency of the STM head should be as large as possible, and the one of the supporting assembly as low as possible.…”

Section: Design and Constructionmentioning

confidence: 99%

Imaging superconducting vortex cores and lattices with a scanning tunneling microscope

Suderow¹,

Guillamón²,

Rodrigo³

et al. 2014

Supercond. Sci. Technol.

101

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Abstract. The observation of vortices in superconductors was a major breakthrough in developing the conceptual background for superconducting applications. Each vortex carries a flux quantum, and the magnetic field radially decreases from the center. Techniques used to make magnetic field maps, such as magnetic decoration, give vortex lattice images in a variety of systems. However, strong type II superconductors allow penetration of the magnetic field over large distances, of order of the magnetic penetration depth λ. Superconductivity survives up to magnetic fields where, for imaging purposes, there is no magnetic contrast at all. Static and dynamic properties of vortices are largely unknown at such high magnetic fields. Reciprocal space studies using neutron scattering have been employed to obtain insight into the collective behavior. But the microscopic details of vortex arrangements and their motion remain difficult to obtain. Direct real space visualization can be made using scanning tunneling microscopy and spectroscopy (STM/S). Instead of using magnetic contrast, the electronic density of states describes spatial variations of the quasiparticle and pair wavefunction properties. These are of order of the superconducting coherence length ξ, which is much smaller than λ. In principle, individual vortices can be imaged using STM up to the upper critical field where vortex cores, of size ξ, overlap. In this review, we describe recent advances in vortex imaging made with scanning tunneling microscopy and spectroscopy. We introduce the technique and discuss vortex images which reveal the influence of the Fermi surface distribution of the superconducting gap on the internal structure of vortices, the collective behavior of the lattice in different materials and conditions, and the observation of vortex lattice melting. We consider challenging lines of work, which include imaging vortices in nanostructures, multiband and heavy fermion superconductors, single layers and van-der-Waals crystals, studying current driven dynamics and the liquid vortex phases.

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Section: Design and Constructionmentioning

confidence: 99%

Imaging superconducting vortex cores and lattices with a scanning tunneling microscope

Suderow¹,

Guillamón²,

Rodrigo³

et al. 2014

Supercond. Sci. Technol.

101

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“…These tips have been characterized for their use in STM proving that the carbon tip apex is not contaminated. 14 We have also ruled out the possibility that the carbon tip is contaminated or wetted by gold atoms of the surface. 15 Single-molecule junctions are obtained by repeatedly forming and breaking the contact between the tip and a gold substrate covered with a self-assembled monolayer (SAM) of molecules.…”

mentioning

confidence: 99%

Carbon tips as electrodes for single-molecule junctions

Castellanos-Gómez

Bilan

Zotti

et al. 2011

Applied Physics Letters

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The following article appeared in Applied Physics Letters vol 99,12 (2011): 123105 and may be found at http://scitation.aip.org/content/aip/journal/apl/99/12/10.1063/1.3643031?showFTTab=true&containerItemId=content/aip/journal/aplWe study electron transport through single-molecule junctions formed by an octanethiol molecule bonded with the thiol anchoring group to a goldelectrode and the opposing methyl endgroup to a carbon tip. Using the scanning tunneling microscope based break junction technique, we measure the electrical conductance of such molecular junctions. We observe the presence of well-defined conductance plateaus during the stretching of the molecular bridge, which is the signature of the formation of a molecular junction.Acknowledges fellowship support from the Comunidad de Madrid (Spain). This work was supported by MICINN (Spain) through the programs MAT2008-01735 and CONSOLIDER-INGENIO-2010 CSD-2007-00010, by Comunidad de Madrid through the program NANOBIOMAGNET S2009/MAT1726, by the EU through the networks BIMORE (MRTN-CT-2006-035859),and by the EC through the network FP7 ITN “FUNMOLS”Project Number 212942

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“…A tube connects the container (2), through a regulating valve (3) to a heat exchanger immersed into liquid nitrogen (4). Helium flows out of the heat exchanger through a usual Helium transfer tube (5) into the cryostat (6). A valve (7) connects the recovery of the cryostat to the Helium recovery line of the laboratory.…”

Section: Closed Cycle Helium Gas Precooling Systemmentioning

confidence: 99%

Methods to simplify cooling of liquid Helium cryostats

et al. 2019

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Liquid Helium is used widely, from hospitals to characterization of materials at low temperatures. Many experiments at low temperatures require liquid Helium, particularly when vibration isolation precludes the use of cryocoolers and when one needs to cool heavy equipment such as superconducting coils. Here we describe methods to simplify the operations required to use liquid Helium by eliminating the use of high pressure bottles, avoiding blockage and improving heating and cooling rates. First we show a simple and very low cost method to transfer liquid Helium from a transport container into a cryostat that uses a manual pump having pumping and pressurizing ports, giving a liquid Helium transfer rate of about 100 liters an hour. Second, we describe a closed cycle circuit of Helium gas cooled in an external liquid nitrogen bath that allows precooling a cryogenic experiment without inserting liquid nitrogen into the cryostat, eliminating problems associated to the presence of nitrogen around superconducting magnets. And third, we show a sliding seal assembly and an inner vacuum chamber design that allows inserting large experiments into liquid Helium.

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A low temperature scanning tunneling microscope for electronic and force spectroscopy

Cited by 25 publications

References 18 publications

Imaging superconducting vortex cores and lattices with a scanning tunneling microscope

Imaging superconducting vortex cores and lattices with a scanning tunneling microscope

Carbon tips as electrodes for single-molecule junctions

Methods to simplify cooling of liquid Helium cryostats

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