Atomic resolution and vortex lattice studies of magnetic superconductors: A first approach in the nickel borocarbide TmNi2B2C

Guillamón, Isabel; Crespo, Manuel; Suderow, Hermann; Vieira, S.; Brison, Jean-Pascal; Bud’ko, Sergey L.; Canfield, Paul C.

doi:10.1016/j.physc.2010.02.073

Cited by 10 publications

(11 citation statements)

References 54 publications

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“…In the nonmagnetic nickel borocarbide LuNi 2 B 2 C, when the magnetic field is applied along the c axis of the tetragonal crystal structure, the vortex lattice is square at high fields, with a side along [110] [13,[54][55][56][57]. The interaction between crystal and vortex lattices is mediated by nonlocal effects, which introduce terms in the vortex-vortex interaction whose in-plane behavior depends on the shape of the Fermi surface [13,[54][55][56][57][58][59]. In β-Bi 2 Pd, the vortex lattice is hexagonal and oriented along the in-plane directions of the square crystal lattice [100] and [010].…”

Section: Discussionmentioning

confidence: 99%

Magnetic field dependence of the density of states in the multiband superconductorβ−Bi2Pd

et al. 2015

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We present very low-temperature scanning tunneling microscopy (STM) experiments on single-crystalline samples of the superconductor β-Bi 2 Pd. We find a single superconducting gap from the zero-field tunneling conductance. However, the magnetic field dependence of the intervortex tunneling conductance is higher than the one expected in a single-gap superconductor. Such an increase in the intervortex tunneling conductance has been found in superconductors with multiple superconducting gaps. We also find that the hexagonal vortex lattice is locked to the square atomic lattice as expected in crystalline superconductors with anisotropic Fermi surfaces. Moreover, we compare the upper critical field H c2 (T ) obtained in our sample with previous measurements and find that H c2 (T ) does not increase by reducing the mean free path. We fit H c2 (T ) and show that multiband Fermi surface is needed to explain the observed behavior. We propose that β-Bi 2 Pd is a single-gap multiband superconductor. We anticipate that single-gap superconductivity might often occur in compounds with anisotropic multiband Fermi surfaces.

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Section: Discussionmentioning

confidence: 99%

Magnetic field dependence of the density of states in the multiband superconductorβ−Bi2Pd

et al. 2015

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“…The rare earths in these compounds possibly interact through exchange mediated by the superconducting electrons. Atomic resolution, and a structural transition from hexagonal to square lattice was observed in the vortex lattice of TmNi 2 B 2 C [170]. Gapless superconductivity was observed in ErNi 2 B 2 C [169].…”

Section: Unconventional Superconductivitymentioning

confidence: 92%

“…A pulling rope moves the holder and breaks the crystal in-situ, exposing a fresh surface. The sample holder is then released to its original position below the tip [154,169,170]. Samples of several tens of µm have been measured using this technique.…”

Section: Methodsmentioning

confidence: 99%

Imaging superconducting vortex cores and lattices with a scanning tunneling microscope

Suderow¹,

Guillamón²,

Rodrigo³

et al. 2014

Supercond. Sci. Technol.

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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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“…[11][12][13][14][15][16][17][18] Superconducting properties have been shown to be enhanced by an external field. [19][20][21][22][23] In heavy fermions and in hybrid proximity ferromagnetic-superconducting structures, magnetism can induce unconventional p-wave or other forms of complex superconductivity. [24][25][26][27][28] NiBi 3 is an intermetallic alloy known to be a type-II superconductor 29 with a critical temperature of about 4 K. Normally, Ni tends to lose its magnetic moment within this type of compound.…”

Section: Introductionmentioning

confidence: 99%

Superconductivity and magnetism on flux-grown single crystals of NiBi3

et al. 2013

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We present resistivity, magnetization, and specific-heat measurements on flux-grown single crystals of NiBi 3 . We find typical behavior of a type-II superconductor, with, however, a sizable magnetic signal in the superconducting phase. There is a hysteretic magnetization characteristic of a ferromagnetic compound. By following the magnetization as a function of temperature, we find a drop at temperatures corresponding to the Curie temperature of ferromagnetic amorphous Ni. Thus, we assign the magnetism in NiBi 3 crystals to amorphous Ni impurities.

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Atomic resolution and vortex lattice studies of magnetic superconductors: A first approach in the nickel borocarbide TmNi2B2C

Cited by 10 publications

References 54 publications

Magnetic field dependence of the density of states in the multiband superconductorβ−Bi2Pd

Magnetic field dependence of the density of states in the multiband superconductorβ−Bi2Pd

Imaging superconducting vortex cores and lattices with a scanning tunneling microscope

Superconductivity and magnetism on flux-grown single crystals of NiBi3

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