[Problem] To provide a phononic material that exhibits an electrical resistance characteristic less than or equal to 0Ω, a precursor of the same, and a method for producing these. [Solution] A phononic material 1 has a periodic structure body 2′ in which structures 3 are periodically and regularly disposed in a constituent 2. The periodic structure body 2′ exhibits an electrical resistance characteristic less than or equal to 0Ω, and has a temperature region that exhibits the electrical resistance characteristic in a temperature range exceeding a superconducting transition temperature when the constituent 2 has the superconducting transition temperature. A method for producing a precursor of the phononic material 1 includes a pretreatment process to obtain the precursor by carrying out a heat treatment to warm the periodic structure body after cooling the periodic structure body in a state of applying a unidirectional current to the periodic structure body 2′.

Electrical, mechanical, computing, and/or other devices that include components formed of extremely low resistance (ELR) materials, including, but not limited to, modified ELR materials, layered ELR materials, and new ELR materials, are described.

An oxide superconductor according to an embodiment includes an oxide superconducting layer includes a single crystal having a continuous perovskite structure containing at least one rare earth element selected from the group consisting of yttrium, lanthanum, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium, barium, and copper, containing praseodymium in a part of the site of the rare earth element in the perovskite structure, and having a molar ratio of praseodymium of 0.00000001 or more and 0.2 or less with respect to the sum of the at least one rare earth element and praseodymium; fluorine in an amount of 2.0×10.sup.15 atoms/cc or more and 5.0×10.sup.19 atoms/cc or less; and carbon in an amount of 1.0×10.sup.17 atoms/cc or more and 5.0×10.sup.20 atoms/cc or less.

According to various implementations of the invention, high quality a-axis XBCO may be grown with low surface roughness. According to various implementations of the invention, low surface roughness may be obtained by: 1) adequate substrate preparation; 2) calibration of flux rates for constituent atoms; and/or 3) appropriate control of temperature during crystal growth. According to various implementions of the invention, a wafer comprises a smoothing layer of c-axis XBCO; a first conducting layer of a-axis XBCO formed on the smoothing layer; an insulating layer formed on the first conducting layer; and a second conducting layer of a-axis XBCO formed on the insulating layer, where, for a same surface roughness, a thickness of the smoothing layer and the first conducting layer combined is greater than a thickness of the first conducting layer without the smoothing layer. According to various implementations of the invention, a Josephson Junction is etched out of the XBCO/insulating layer/XBCO trilayer by: ion mill etching the top XBCO layer and some of the insulating layer to intentionally leave some of the insulating layer on the bottom XBCO layer; and/or ion mill etching at least the insulating layer at an off angle to reduce or minimize ion damage to the bottom XBCO layer otherwise introduced by the ion mill.

According to various implementations of the invention, high quality a-axis XBCO may be grown with low surface roughness. According to various implementations of the invention, low surface roughness may be obtained by: 1) adequate substrate preparation; 2) calibration of flux rates for constituent atoms; and/or 3) appropriate control of temperature during crystal growth. According to various implementations of the invention, a wafer comprises a smoothing layer of c-axis XBCO; a first conducting layer of a-axis XBCO formed on the smoothing layer; an insulating layer formed on the first conducting layer; and a second conducting layer of a-axis XBCO formed on the insulating layer, where, for a same surface roughness, a thickness of the smoothing layer and the first conducting layer combined is greater than a thickness of the first conducting layer without the smoothing layer.

A connection structure for a superconducting layer according to an embodiment includes a first superconducting layer; a second superconducting layer; and a connection layer disposed between the first superconducting layer and the second superconducting layer, the connection layer including crystal grains containing a rare earth element (RE), barium (Ba), copper (Cu), and oxygen (O), the crystal grains having a grain size distribution including a bimodal distribution. The bimodal distribution includes a first distribution including a first peak and a second distribution including a second peak. A first grain size corresponding to the first peak is larger than a second grain size corresponding to the second peak. Among the crystal grains, crystal grains having a grain size corresponding to the first distribution include a crystal grain having a plate shape or a flat shape.

Operational characteristics of an high temperature superconducting (“HTS”) film comprised of an HTS material may be improved by depositing a modifying material onto appropriate surfaces of the HTS film to create a modified HTS film. In some implementations of the invention, the HTS film may be in the form of a “c-film.” In some implementations of the invention, the HTS film may be in the form of an “a-b film,” an “a-film” or a “b-film.” The modified HTS film has improved operational characteristics over the HTS film alone or without the modifying material. Such operational characteristics may include operating in a superconducting state at increased temperatures, carrying additional electrical charge, operating with improved magnetic properties, operating with improved mechanic properties or other improved operational characteristics. In some implementations of the invention, the HTS material is a mixed-valence copper-oxide perovskite, such as, but not limited to YBCO. In some implementations of the invention, the modifying material is a conductive material that bonds easily to oxygen, such as, but not limited to, chromium.

A superconducting structure is presented. In some embodiments, the superconducting structure includes a first plane of material; a second plane of material; and a separating medium positioned between the first plane and the second plane, wherein a superconducting critical temperature of the superconducting structure is adjusted by control of one or more parameters.

A superconductor device includes a high superconductivity transition temperature enhanced from the raw material transition temperature. The superconductor device includes a matrix material and a core material. The enhancing matrix material and the core material together create a system of strongly coupled carriers. A plurality of low-dimensional conductive features can be embedded in the matrix. The low-dimensional conductive features (e.g., nanowires or nanoparticles) can be conductors or superconductors. An interaction between electrons of the low-dimensional conductive features and the enhancing matrix material can promote excitations that increase a superconductivity transition temperature of the superconductor device.

Operational characteristics of an high temperature superconducting (“HTS”) film comprised of an HTS material may be improved by depositing a modifying material onto appropriate surfaces of the HTS film to create a modified HTS film. In some implementations of the invention, the HTS film may be in the form of a “c-film.” In some implementations of the invention, the HTS film may be in the form of an “a-b film,” an “a-film” or a “b-film.” The modified HTS film has improved operational characteristics over the HTS film alone or without the modifying material. Such operational characteristics may include operating in a superconducting state at increased temperatures, carrying additional electrical charge, operating with improved magnetic properties, operating with improved mechanic properties or other improved operational characteristics. In some implementations of the invention, the HTS material is a mixed-valence copper-oxide perovskite, such as, but not limited to YBCO. In some implementations of the invention, the modifying material is a conductive material that bonds easily to oxygen, such as, but not limited to, chromium.