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Schematic view of STM assembly below the mixing chamber plate. (a) and (b) show the computer aided design model and real images, respectively.
(a) Sample cleaver. The sample cleaver is mounted at the 4 K-plate of the cryostat. It acts at the same time as a radiation shield to block thermal radiation from room temperature. The cleaving mechanism is operated by the sample transfer mechanism, allowing for transfer of the sample into the inner vacuum only after cleavage, (b) Shutter for thermal radiation shielding. The shutter is mounted on the still plate to block thermal radiation from the 4 K-plate from reaching the sample. The shutter is opened and closed by rotation of the manipulator similar to the cleaver.
(a) Atomically resolved topography of a cleaved NbSe2 surface (12 × 12 nm2, V = 90 mV, and I = 0.5 nA) measured at T MXC ≈ 10 mK. Besides the surface atomic structure, a modulation due to formation of a charge density wave can be seen. (b) Line cut along an atomic row, it can be seen that the residual noise is below 15 pm. 42 (c) Spatially averaged spectra taken on NbSe2 (spectroscopy set-point: V = 90 mV, I = 1 nA, lock-in modulation of 100μV, and frequency of 511 Hz) at base temperature, the solid line shows a fit of Eq. (1) to the data.
Tunneling spectroscopy of a gold-vacuum-aluminum-junction at T MXC ≈ 10 mK with V = 2 mV and I = 3 nA (a) Fit of Eq. (4) to a spectrum of the Au-vacuum-Al junction for a lock-in modulation of 5 μV, yielding an electronic temperature of ≈140 mK. (b) Tunneling spectroscopy as a function of applied magnetic field. The superconducting gap disappears at magnetic fields on the order of 30 mT. (c) and (d) Tunneling and calculated spectra as a function of lock-in modulation (frequency: 511 Hz).
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