Vortex states in high-T_c superconductors and superconductivity in modern nano-science and engineering

Abstract

A brief review is given on the recent development of the vortex engineering research in our group with special emphasis on the geometrical confinement of vortices into micron-size of samples. We show that the static as well as dynamical nature of vortices is strongly affected by the geometrical constraints, which can be manipulated by the recent nano-technology engineering artificially. One of the spectacular phenomena in this context is a formation of self-organized vortex structures occuring both in static and dynamic manners. The static behaviors have been studied by the scanning SQUID microscope technique and the dynamical behaviors are mostly done in transport measurements. Some technical development of these methods is also discussed. We stress that a common generic concept here is the confinement in nano-scale superconducting systems by the existing surfaces (boundaries), which plays an essential role for the phenomena. Some typical examples are shown, such as results on the vortex arrangement in micron size superconducting disks, a formation of the giant vortex state in such a particular case and the dynamical effects of vortices, especially in the case of Josephson vortices confined in an intrinsic Josephson junction in micron size single crystal Bi 2 Sr 2 CaCu 2 O 8Cd , where the dynamical effect of the confinement provides rich linear and non-linear phenomena due to the excitation of Josephson plasma. Making use of Josephson plasma excitations, a generator operating at T (Hz) frequencies is proposed in this intrinsic Josephson junctions. These phenomena are expected to be all beneficial to potential applications. q

Phase purity and surface morphology of high-J superconducting Bi2Sr2Ca1Cu2O8+δ thin films

“…Thin film applications exploiting the quasi-2D transport properties of HTS materials require epitaxial layers that are grown on lattice matched substrates or buffer layers. HTS thin films of well-defined unit cell lattice orientation offer several device applications, for instance, as THz radiation emitters [1][2][3][4]. Such films are also ideal materials to study the properties of the magnetic flux quanta (vortices) and vortex lattices.…”

Crossover from paramagnetic to diamagnetic ac-susceptibility in Bi2Sr2CaCu2O${}_{8+\delta }$ superconductor for ${\bf{H}}| | c \mbox{-} {\rm{axis}}$

“…(Bi-2212) superconductor [6][7][8][9][10][11][12][13][14]. Zeldov and co-workers using a Bi-2212 single crystal and local Hall magnetometer measurements, discovered a clear discontinuous change of the magnetization, attributed to the vortex lattice melting transition [15].…”