UHV compatible 3He – 4He dilution refrigerators for STM in high magnetic field

Shvarts, Vladimir; Zhao, Ziyi; Bobb, Lorraine; Jirmanus, M.

doi:10.1088/1742-6596/150/1/012046

Cited by 6 publications

(6 citation statements)

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“…The right-hand focal point of the preparation chamber has an e-beam heater stage with an Ar ion sputter gun pointed at it (dark blue). methods has been successfully implemented in a number of systems [9][10][11] . The remaining difficulty lies in devising a scheme to transfer tips and samples between various UHV stages and the microscope.…”

Section: Fig 1 (A)mentioning

confidence: 99%

“…The successful integration of a dilution refrigerator into an ultra-high vacuum environment has the unmeasurable benefit for scanning tunneling microscopy that the full range of samples available to the technique could be studied, and standard techniques for the in situ preparation of tips and samples could be used without alteration. Although standard dilution refrigerators contain materials, such as nylon, brass and soft solder, which are anathema to ultra high vacuum, substitution by UHVcompatible materials (PEEK, OFHC copper, and high temperature solder) and the adoption of proper cleaning methods has been successfully implemented in a number of systems [9][10][11] . The remaining difficulty lies in devising a scheme to transfer tips and samples between various UHV stages and the microscope.…”

Section: Ultra-high Vacuum Assemblymentioning

confidence: 99%

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Design and performance of an ultra-high vacuum scanning tunneling microscope operating at dilution refrigerator temperatures and high magnetic fields

Misra

Zhou

Drozdov

et al. 2013

Review of Scientific Instruments

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We describe the construction and performance of a scanning tunneling microscope (STM) capable of taking maps of the tunneling density of states with sub-atomic spatial resolution at dilution refrigerator temperatures and high (14 T) magnetic fields. The fully ultra-high vacuum system features visual access to a two-sample microscope stage at the end of a bottom-loading dilution refrigerator, which facilitates the transfer of in situ prepared tips and samples. The two-sample stage enables location of the best area of the sample under study and extends the experiment lifetime. The successful thermal anchoring of the microscope, described in detail, is confirmed through a base temperature reading of 20 mK, along with a measured electron temperature of 250 mK. Atomically-resolved images, along with complementary vibration measurements, are presented to confirm the effectiveness of the vibration isolation scheme in this instrument. Finally, we demonstrate that the microscope is capable of the same level of performance as typical machines with more modest refrigeration by measuring spectroscopic maps at base temperature both at zero field and in an applied magnetic field.PACS numbers: 07.79.Cz,07.79.Fc Scanning tunneling microscopy (STM), since its development almost 30 years ago, has become a powerful technique in condensed matter physics, providing not only structural information about surfaces, but also spectroscopic measurements of the electronic density of states at the atomic length scale. However, most instruments operate at temperatures above 1 K, limiting access to exotic electronic phases and quantum effects expected at lower temperatures, which are studied as a matter of routine by other techniques. Generally, very little spectroscopic information about the electronic density of states is known at dilution refrigerator temperatures, usually being limited to what can be learned using either point contact spectroscopy or planar tunnel junctions. Moreover, STM can make such measurements on the atomic length scale, allowing it to probe systems, such as single spins and atomic chains, which are not directly accessible any other way.While the integration of STM with a dilution refrigerator can be conceptually reduced to simply attaching the microscope to the end of a mixing chamber in lieu of some other cryogenic refrigerator, the technical requirements for sub-Angstrom positioning of an STM tip above an atomically clean surface are often at odds with those for cooling a sample to milli-Kelvin temperatures. For example, when attaching the microscope to the refrigerator, the former would favor the use of a soft mechanical joint using springs, which would isolate vibrations, while a) Electronic mail: yazdani@princeton.edu the latter would favor the use of a rigid mechanical joint with a metal rod, which would provide a strong thermal contact. Nevertheless, a number of STM instruments have been developed that cool the sample using a dilution refrigerator 1-8 . However, among these, few feature ultra-high vacuum (UHV...

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Section: Fig 1 (A)mentioning

confidence: 99%

Section: Ultra-high Vacuum Assemblymentioning

confidence: 99%

Design and performance of an ultra-high vacuum scanning tunneling microscope operating at dilution refrigerator temperatures and high magnetic fields

Misra

Zhou

Drozdov

et al. 2013

Review of Scientific Instruments

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show abstract

“…Note that observation of the conductance oscillations (8) requires a sufficiently strong magnetic field. Currently in low-temperature STM magnetic fields up to 15T are reachable [12]. For example, in order to observe a quarter period H for z 0 = d = 20 nm it is necessary to apply a field of H = 5T .…”

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confidence: 99%

Aharonov-Bohm type oscillations in the system of two tunnel point-contacts in the presence of single scatterer: determination of the depth of the buried impurity

Khotkevych

Kolesnichenko

Ruitenbeek

2012

J. Phys.: Conf. Ser.

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The conductance of a system containing two tunnel point-contacts and a single subsurface scatterer in the presence of a magnetic field is investigated theoretically. A general formula for the dependence of the conductance on the distance between contacts, the defect position, and the magnetic field is obtained. It is shown that in the presence of a magnetic field the conductance undergoes Aharonov-Bohm type oscillations. We find a simple relation between the period of the oscillations and the depth of the subsurface impurity. On the basis of this fact a new and easy method of determination the depth of the buried impurity is proposed.

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“…Currently in low temperature STM the magnetic field up to 15T is reachable [23]. For example, in order to observe the quote of period ∆H for z 0 = d =20 nm it is necessary to apply the field H = 5T.…”

mentioning

confidence: 99%

“…Note that observation of the conductance oscillations (34) requires a sufficiently strong magnetic field. Currently in low temperature STM the magnetic field up to 15T is reachable [23]. For example, in order to observe the quote of period ∆H for z 0 = d =20 nm it is necessary to apply the field H = 5T.…”

mentioning

confidence: 99%

Quantum interference effects in a system of two tunnel point-contacts in the presence of a single scatterer: simulation of a double-tip STM experiment

Khotkevych

Kolesnichenko

Ruitenbeek

2011

Low Temperature Physics

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The conductance of systems containing two tunnel point-contacts and a single subsurface scatterer is investigated theoretically. The problem is solved in the approximation of s-wave scattering giving analytical expressions for the wave functions and for the conductance of the system. Conductance oscillations resulting from the interference of electron waves passing through different contacts and their interference with the waves scattered by the defect are analyzed. The prospect for determining the depth of the impurity below the metal surface by using the dependence of the conductance as a function of the distance between the contacts is discussed. It is shown that the application of an external magnetic field results in Aharonov-Bohm type oscillations in the conductance, the period of which allows detection of the depth of the defect in a double tip STM experiment.

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UHV compatible 3He – 4He dilution refrigerators for STM in high magnetic field

Cited by 6 publications

References 0 publications

Design and performance of an ultra-high vacuum scanning tunneling microscope operating at dilution refrigerator temperatures and high magnetic fields

Design and performance of an ultra-high vacuum scanning tunneling microscope operating at dilution refrigerator temperatures and high magnetic fields

Aharonov-Bohm type oscillations in the system of two tunnel point-contacts in the presence of single scatterer: determination of the depth of the buried impurity

Quantum interference effects in a system of two tunnel point-contacts in the presence of a single scatterer: simulation of a double-tip STM experiment

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