Abstract:We theoretically demonstrate that the high-critical-temperature (high-Tc) superconductor Bi2Sr2CaCu2O8+x (BSCCO) is a natural candidate for the recently envisioned classical space-time crystal. BSCCO intrinsically forms a stack of Josephson junctions. Under a periodic parametric modulation of the Josephson critical current density, the Josephson currents develop coupled space-time crystalline order, breaking the continuous translational symmetry in both space and time. The modulation frequency and amplitude sp… Show more
“…3 c. Figure 3 d shows the dc I–V characteristics for the temperature range of 70 K to 90 K. In Fig. 4 b we observe the critical current density of a nominally 0° twisted junction at 10 K is ~ 1.34 kA/cm 2 which is comparable to the critical current density of the intrinsic Josephson junctions in the bulk BSCCO 28 ; this is direct evidence of the high-quality nature of the junctions made by the cryogenic exfoliation method. Figure 3 ( a ) Optical image of a 0° twisted BSCCO device.…”
Section: Electrical Characterization Of Fabricated Twisted Bscco Devicesmentioning
Assembling atomic layers of van der Waals materials (vdW) combines the physics of two materials, offering opportunities for novel functional devices. Realization of this has been possible because of advancements in nanofabrication processes which often involve chemical processing of the materials under study; this can be detrimental to device performance. To address this issue, we have developed a modified micro-manipulator setup for cryogenic exfoliation, pick up, and transfer of vdW materials to assemble heterostructures. We use the glass transition of a polymer PDMS to cleave a flake into two, followed by its pick-up and drop to form pristine twisted junctions. To demonstrate the potential of the technique, we fabricated twisted heterostructure of Bi2Sr2CaCu2O8+x (BSCCO), a van der Waals high-temperature cuprate superconductor. We also employed this method to re-exfoliate NbSe2 and make twisted heterostructure. Transport measurements of the fabricated devices indicate the high quality of the artificial twisted interface. In addition, we extend this cryogenic exfoliation method for other vdW materials, offering an effective way of assembling heterostructures and twisted junctions with pristine interfaces.
“…3 c. Figure 3 d shows the dc I–V characteristics for the temperature range of 70 K to 90 K. In Fig. 4 b we observe the critical current density of a nominally 0° twisted junction at 10 K is ~ 1.34 kA/cm 2 which is comparable to the critical current density of the intrinsic Josephson junctions in the bulk BSCCO 28 ; this is direct evidence of the high-quality nature of the junctions made by the cryogenic exfoliation method. Figure 3 ( a ) Optical image of a 0° twisted BSCCO device.…”
Section: Electrical Characterization Of Fabricated Twisted Bscco Devicesmentioning
Assembling atomic layers of van der Waals materials (vdW) combines the physics of two materials, offering opportunities for novel functional devices. Realization of this has been possible because of advancements in nanofabrication processes which often involve chemical processing of the materials under study; this can be detrimental to device performance. To address this issue, we have developed a modified micro-manipulator setup for cryogenic exfoliation, pick up, and transfer of vdW materials to assemble heterostructures. We use the glass transition of a polymer PDMS to cleave a flake into two, followed by its pick-up and drop to form pristine twisted junctions. To demonstrate the potential of the technique, we fabricated twisted heterostructure of Bi2Sr2CaCu2O8+x (BSCCO), a van der Waals high-temperature cuprate superconductor. We also employed this method to re-exfoliate NbSe2 and make twisted heterostructure. Transport measurements of the fabricated devices indicate the high quality of the artificial twisted interface. In addition, we extend this cryogenic exfoliation method for other vdW materials, offering an effective way of assembling heterostructures and twisted junctions with pristine interfaces.
“…So far the concept of space-time group has received considerable attentions [109][110][111][112][113][114][115][116][117][118] . We expect it would serve as a guiding principle for quantum dynamic studies, in analogy to the role of space group to static crystalline symmetries 9 .…”
Section: F Discussionmentioning
confidence: 99%
“…Instead, the timedependent motions of lattice ions should be treated at the zeroth order, i.e., we should include them in the timedependent lattice potential of the Schrödinger equation. In artificial lattices, such as the phononic, photonic crystals, and optical lattice for ultracold atoms, lattice potentials could be manipulated on purpose 36,109,116 , In these cases, space-time group should replace space group as the symmetry guidance of quantum dynamics.…”
Symmetry distills the simplicity of natural laws from the complexity of physical phenomena. The symmetry principle is of vital importance in various aspects of modern physics, including analyzing atomic spectra, determining fundamental interactions in the Standard Model, and unifying physics at different energy scales. In this chapter, novel applications of this principle are reviewed in condensed matter physics and cold atom physics for exploring new states of matter.First, the concept of space-time group generalizes crystalline space group symmetries to their dynamic counterparts, including nonsymmorphic space-time symmetries (e.g. time-screw rotation, time-glide reflection, and time-shift rotary reflection). It includes and goes beyond the Floquet theory framework, and applies to a large class of dynamic systems such as laser-driven solid crystals, dynamic photonic crystals, and optical lattices, etc. Second, the perspective of high symmetries (e.g. SU(N ) and Sp(N )) bridges large-spin cold fermion systems with high energy physics. For example, a generic SO(5), or, isomorphically Sp(4) symmetry is proved in spin-3 2 systems. Moreover, an exact SO(7) symmetry is identified as possessing an extraordinary unifying power: Its χ-pairing operator extends Yang's η-pairing to a high-rank Lie algebra, integrating 21 orders in both particle-hole and particle-particle channels into a unified framework. Such systems also exhibit multi-fermion orderings, including quartetting superfluidity (charge 4e) and quartet density wave, which are α-particle-like, or, baryon-like orderings. The resonant quantum plaquette states of SU(4) antiferromagnetism are described by a high-order gauge theory. A quantum phase transition occurs from the Slater region to the Mott region in the SU(6) Hubbard model. A tendency of convergence of itineracy and locality is revealed in 1D SU(N ) systems as N goes large. Third, a new mechanism is presented to generate spin-orbit coupling based on "spin-from-isospin" via manybody Fermi surface instabilities of the Pomeranchuk type. In contrast, the conventional wisdom views spin-orbit coupling as a single-body relativistic effect. This mechanism generalizes itinerant ferromagnetism to the unconventional symmetry versions (e.g. p-wave), which can also be viewed as magnetic multipolar orderings in momentum space.
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