A 350 mK, 9 T scanning tunneling microscope for the study of superconducting thin films on insulating substrates and single crystals

Kamlapure, Anand; Saraswat, Garima; Ganguli, Somesh Chandra; Bagwe, Vivas; Raychaudhuri, Pratap; Pai, S. P.

doi:10.1063/1.4849616

Cited by 25 publications

(16 citation statements)

References 25 publications

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“…The VL was imaged using a home-built scanning tunneling microscope 43 (STM) operating down to 350 mK and fitted with an axial 90 kOe superconducting solenoid. Prior to STM measurements, the crystal is cleaved in-situ in vacuum, giving atomically smooth facets larger than 1 μm × 1 μm.…”

Section: Methodsmentioning

confidence: 99%

Disordering of the vortex lattice through successive destruction of positional and orientational order in a weakly pinned Co0.0075NbSe2 single crystal

Ganguli

Singh

Saraswat

et al. 2015

Sci Rep

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The vortex lattice in a Type II superconductor provides a versatile model system to investigate the order-disorder transition in a periodic medium in the presence of random pinning. Here, using scanning tunnelling spectroscopy in a weakly pinned Co0.0075NbSe2 single crystal, we show that the vortex lattice in a 3-dimensional superconductor disorders through successive destruction of positional and orientational order, as the magnetic field is increased across the peak effect. At the onset of the peak effect, the equilibrium quasi-long range ordered state transforms into an orientational glass through the proliferation of dislocations. At a higher field, the dislocations dissociate into isolated disclination giving rise to an amorphous vortex glass. We also show the existence of a variety of additional non-equilibrium metastable states, which can be accessed through different thermomagnetic cycling.

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Section: Methodsmentioning

confidence: 99%

Disordering of the vortex lattice through successive destruction of positional and orientational order in a weakly pinned Co0.0075NbSe2 single crystal

Ganguli

Singh

Saraswat

et al. 2015

Sci Rep

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“…STS measurements were performed in a home-built scanning tunneling microscope (STM) down to 450 mK and fitted with 90 kOe superconducting solenoid 19 . For STS measurements, post deposition, the film was transferred in the scanning tunneling microscope using an ultrahigh vacuum suitcase without exposure to air.…”

Section: Sample and Experimental Detailsmentioning

confidence: 99%

Evidence of zero-point fluctuation of vortices in a very weakly pinned a -MoGe thin film

et al. 2021

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In a Type II superconductor, the vortex core behaves like a normal metal. Consequently, the single-particle density of states in the vortex core of a conventional Type II superconductor remains either flat or (for very clean single crystals) exhibits a peak at zero bias due to the formation of Caroli-de Gennes-Matricon bound state inside the core. Here we report an unusual observation from scanning tunneling spectroscopy measurements in a weakly pinned thin film of the conventional s-wave superconductor a-MoGe, namely, that a soft gap in the local density of states continues to exist even at the center of the vortex core. We ascribe this observation to rapid fluctuation of vortices about their mean position that blurs the boundary between the gapless normal core and the gapped superconducting region outside. Analyzing the data as a function of magnetic field we show that the variation of fluctuation amplitude as a function of magnetic field is consistent with quantum zero-point motion of vortices.

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“…2S(b)). The inductive and dissipative components of the mutual inductance (M = M' -iM'') between the two were measured by passing a small 31 Vortex lattice imaging using STS: We imaged the VL using a home-built low temperature scanning tunneling microscope 44 (STM) operating down to 350 mK and fitted with a 90 kOe superconducting solenoid. To obtain VL images, spatially resolved tunneling conductance (dI/dV) was measured at different field using a Pt-Ir tip.…”

Section: Low Frequency Penetration Depthmentioning

confidence: 99%

Melting of the Vortex Lattice through Intermediate Hexatic Fluid in an a−MoGe Thin Film

et al. 2019

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The hexatic fluid refers to a phase in between a solid and a liquid which has short range positional order but quasi-long range orientational order. In the celebrated theory of Berezinskii, Kosterlitz and Thouless and subsequently refined by Halperin, Nelson and Young, it was predicted that a 2-dimensional hexagonal solid can melt in two steps: first, through a transformation from a solid to a hexatic fluid which retains quasi long range orientational order and then from a hexatic fluid to an isotropic liquid. In this paper, using a combination of real space imaging and transport measurements we show that the 2dimensional vortex lattice in a-MoGe thin film follows this sequence of melting as the magnetic field is increased. Identifying the signatures of various transitions on the bulk transport properties of the superconductor, we construct a vortex phase diagram for a two dimensional superconductor.

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A 350 mK, 9 T scanning tunneling microscope for the study of superconducting thin films on insulating substrates and single crystals

Cited by 25 publications

References 25 publications

Disordering of the vortex lattice through successive destruction of positional and orientational order in a weakly pinned Co0.0075NbSe2 single crystal

Disordering of the vortex lattice through successive destruction of positional and orientational order in a weakly pinned Co0.0075NbSe2 single crystal

Evidence of zero-point fluctuation of vortices in a very weakly pinned a -MoGe thin film

Melting of the Vortex Lattice through Intermediate Hexatic Fluid in an a−MoGe Thin Film

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